F22 is the better motor all around, it may be an opinion but I find it factual. A fully bolted f20 won't touch a fully bolted f22. Also the f22 has the strengthened valve retainers. And all the f22s come with the upgraded oil banjo squirters, unlike earlier f20s.

 

F22 ----> no oil burning, better power and torque through out the whole rpm. Revs to 8500 or even 9000 RPMs easily. F22 motor from 04-05 s2k's are plug and play, So why not?

 

Id just buy a new shortblock from honda and rebuild your current head. I think the shortblock runs about 3000-3500$. Have a shop that is well vested with the s2000 do the install.