y does it matter what the japanese use for octane? you're in america. so...just go with 93 octane if you get one of those jdm engines.
from a purely speculative pov, i would imagine you'd have to take out the firewall completely and replace it with a jdm one. either that or cut a hole for the steering column on the right side.
anyway, don't get overly ambitious. you're still bidding, which is different from buying the car.