If you go to a NA-route your car needs a manual transmission.
Then you had to change valves to 46/38 and port the head you need something about 220cfm of flow, it is not easy, but it is possible.
You need to skim the cylinder head, you need 11:1-12.5:1 static cr!
Then you need a good camshaft, something about 270degrees of 0-050" and 13mm lift.
Then add good intake manifold, or go to a 2 pieces of FAJS 48mm carburators, then good header and yes, you had a 200hp
It will cost a lot, but not so much than someoone says.
Cylinder head and a camshaft cost 1200€ to me, it is built by LVR-racing engines which makes engines to a group f rallycars, it is a 530 head and it flows about 210cfm at 12mm lift, and little more with bigger lift.
Fajs carbs cost about 280 per piece, so it is 560€. Good header cost about 200€, it adds up to 1200 from head, 560€ from carbs, 200€ from headers, it is 2060€.
If you get a crashed car with b230ft, and you make engine swap it cost about 1000€ and then you had to add so called "little things", fittings, acccessories etc etc, those adds up quickly to 200€, exhaust cost about 500€ etc etc. those little thing adds up that it will cost altogether somthing about 2000€.
So those costs about the same!
But then you quickly get addicted to boost if you go to a turbo route, which had much more headroom. Then you buy bigger turbos, bigger injectors, better intercoolers, tubular exhaust manifold, good plenum intake, then yours lh does not ignite as much as you need to, then you had to buy a microsquirt or something like it, ls coils to ignite the E85 then you had spend thousand of dollars to engine. At this point you need at least forged con rods, and maybe a forged pistons, altough guys in sweden drives with original cast pistons at 550whp. It just need an E85 and a perfect tune.
Remember what i said, boost is addictive, maybe equally to heroin, you will put all yours excessive money to engine. You will surf at acm.se and a kl-racing and a classicswede. You will buy a project engine and you desire a stroker kit at acm, 3000cc crank, rods and pistons cost 1759€, then you had to put away little money from every payvheck until you had money to the stroker kit. Then you read s?varturbo forums and read about rickard thomssons car. There is always room for 3000cc stroker with an ACM aftermarket cylinder head, you save money to this 260cfm cylinder head:
Then you notice that you need a Borg&Warners ball bearing twin scroll turbo, or go to a cheaper route an buy a holset hx55pro.
Then you had spend 15 grand to engine and it produces a 750whp. Then you quickly notice that you need a better transmission, clutch, and rear end. You spend hours and hours to surfing at bakaxels.se, then you notice that they sell everything that you need. Clutch is a 15000 sek, 1500$, it will hold a 1250nm, then you need a transmission, you will surf more at bakaxel.se and you found a G6-53DZ 6-speed transmission, it holds about 900nm, so it might be a good choice. Then you swap, drivehafts to 31spline, and you change rear end to tenaci torsendiff with 31 spline driveshafts, then your rear end will hold at least 1000nm and it goes to original brackets.
You save more money and spend a 4000$ only at bakaxel.se. Then you need bigger brakes and you go to a s60r front discs and double calipers to rear. Then you need a good coilover kit at whole car, you spend 1500$ to this.
Then you have spend money so much that you can buy a little house from the money that you put your old car.
But then you have the ultimate sleeper, you can smoke out some corvettes and vipers and lambos etc.
Remember!
Boost is very very addictive!