Assuming the engine has basically healthy / even compression cold(ish) (tan colored plugs are good)...
0W slippery oil really helps.
Low octane volatile fuel without too much water in it/Aviation anti-gel additives for piston engine aircraft flying in cold fog.
Battery blanket/heater.
Block heat is easier on everything, but the 0W oil and getting a largish battery warm enough to actually pass some current (assuming the connections are clean) is a real problem piece of the puzzle.
You can use a 240-DIesel battery tray and sized battery if you're really paranoid, but it shouldn't be absolutely needed/don't panic.
There was an update for 556 and earlier 561 ECUs to a better cold starting program on the chip as they had problems cranking a little too long and/or borderline flooding out, as those were problematic in the earlier LH2.4 N/A cars. Install a later # ECU, it's well documented on brickboard some of the problems with those.
Later updated LH2.4 ECUs have a MUCH better cold starting program I can attest to if all is tuned up tip top/triple checked and verified to work right and otherwise stock on a later LH2.4 car.
The MAF and coolant temp sensor also need to work properly.
Couldn't tell you on any dirty or kool-aid injectors hacked in there.
Block heat, nice as it is, is sorta a band-aid for the wrong weight oil. 0W modern slippery synthetic oil is really an amazing god-send.
That said, it'll save a lot of engine wear/fuel consumption due to poor fuel atomization, but cold starting should probably be tested ~weekly to verify that it fires and doesn't/won't strand you somewhere that block heat isn't available/potentially remote/life threatening.
Best place for a no-start/cold start test run failure. obviously being in your own driveway...one would think...
Still, with the correct weight oil, block heat etc you can save 20-30% fuel as well as the VAST majority of engine wear & tear when it gets really cold and just test really cold starting ~weekly "just in case" and have heat as soon as you enter the car, test that it starts, shut it down, and block heat it to prevent wasting fuel?
With 2000W(+) 12V inverters so relatively inexpensive now, you ought to be able to heat the block and battery itself with only the starting battery if you wait a minute to first warm the battery even if if you can't plug into grid power (ideal) to accomplish those goals. The poor starting battery and engine will last considerably longer and provide better fuel economy with that done.
There's a (relative) TON of energy in a strong starting battery (even tho it's not "deep cycle") if you can access it by warming it even very slightly and enough to heat a half gallon of coolant/engine block for 10 minutes to pretty warm temps...easily a kilowatt hour or two in there plus enough to hit the starter to crank it over without hurting the battery's lifespan. The block heater is only ~750W-1kw for a really powerful one in most cases screwed into the block...comparable to your coffee maker running for 5-10 mins.
Working airbox t-stat is also good for economy/longevity if the car is N/A.
It's a fine dance at those temps to get it to fire from stone cold, have already scraped your window/ripped the tarp/magnet off the top of it if you planned ahead/avoid scraping it all together if it's parked outside. Then, nnce it fires, you want the airbox t-stat to work feeding it warm regulated ~80?F air mixed off the exhaust which gets hot in about 10-30 seconds and spend as little time as possible running rich/idling/washing the cylinders down and drive it gently at very light load burning as absolutely lean as possible.
TL;DR OT below:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Charging a Tesla or new Nissan leaf with the elaborate liquid coolant battery temp maintaining system in extreme cold is a real challenge for this reason...if the car's outside you're basically just treading water with a 110V 20A circuit.)
The new leaf has an elaborate VRF heat pump to at least *try* to use less energy to deal with heating/cooling the cabin and battery pack, but that cold it's hard for even a heat pump to work/perform its defrost cycle / find much heat without an absurdly large heat exchanger coil and insulated hat to cover the coil for the defrost cycle and a 220/more powerful charging source is needed and/or semi-climate controlled parking space. (Resistance) Pan heater on a heat pump nearly nullifies the efficiency in very cold/very low lying fog conditions, but will get you by in those very adverse conditions. Building an insulated cover for the heat pump to cover it tightly to the ~56?F ground and keep it out of the cold air next to a black painted surface during daylight hours under an eve for the "run against itself" defrost cycle whilst save trying tosave some kilowatts...difficult to automate it like reactor control rods being dropped.
K-jet is better optimized for the cold than LH-EFI, when it works right...the cold start valve sprays a fine mist at 60-80psi very briefly and the fuel injectors are variable nozzles spraying right at the backs of the intake valves instead of waiting forever for the LH-EFI injectors shooting a constant spray pattern/pressure having all the fuel condense on the cold intake port walls until all that coolant/intake reaches operating temp with a bunch of (liekly) very cold to (at best) ~80?F (airbox wax-pellet-t-statically controlled) air flowing over said port walls until they reach ~180?F.
Obviously, you don't want the airbox t-stat to fail on the LH-EFI cars in the summer, at risk of possibly frying the MAF/AMM...so that has to be tested/looked after periodically/seasonally. Doubtful failure of that part has any measurable adverse effects on the longevity of the K-jet cars at all...maybe slightly reduced power under full load in the summer with it malfunctioning/drawing hot air off the exhaust much like leaving the carb heat on in a small airplane?
For very cold weather, I'd put a piece of board over half of the radiator on the intake/airbox side of the engine and de-intercool my 245Turbo for cold running and hook the airbox t-stat back up with the front splash pan on it to keep all of the engine bay sufficiently warm. Note the old 122s (with "hard"/no clutch mechanical fan to be fair) and SAABs had a window shade for half/all of the radiator for cold weather. The fan clutch would never engage the cooling fan whatever until it got above ~20-30F at least even with 1/2 of the radiator surface area missing. Not that anyone these days wants to be bothered to deal with having to actually *do* anything seasonally, just want to get in and go!
Had the intercooler/throttle body ice up on me once in the fog in Canada in a borderline life-threatening moment (just like an old school small piston engine airplane flying in cold fog with carburettor heat off) with no one around for 100km. Air intake temp is only about 70*F non-intercooled on those really cold days anyway!
Best of luck, that's all I know/don't know/have experienced.