I've got a '75 245 through BC emissions by introducing a small
vacuum leak in the right place...
It leaned it out, in practice.
Best strategy is to fail once, and note what you failed on, do
some research, and make adjustments in the direction of fixing
your problem. Even with a carb/k-jet system, you can push it in
the direction you want with the right tweaks.
I can't really recall the Ontario standards, but in BC, you only
need to be as good as the car was when stock. It's low hanging
fruit. If you have retrofitted a modern EFI/IGN system. It is one of
the advantages to owning a seventies 240.
If you are modding an old 240, you can work towards the period
standards with no trouble.
The modern control systems will ensure that your motor does not
blow up. They will be also enough to ensure that your motor will
not spew out egregious amounts of hydrocarbons or CO. If your
motor is running really inefficiently emissions-wise, your motor
will be running really inefficiency power-wise.
A good tune that is good for your track times is just as good as for
your emissions numbers.
Burning fuel for no reason is inefficient, no matter the situation.