Engine swap

the engine will bolt up, but like 273 said you'll need to address the mismatch between the torque converter snout and the crank register.

i know somebody sells one, the last time i picked one up from wildcat autowrecking so you might try there? or you can have one made by a machine shop.

a concern would be the availability of performance torque converters for the early transmission. that being said, you could always send yours out and have it rebuilt to spec.

you'll need different motor mounts for a 340/360, the 318 are the same.