How can I put a 350 in a MKIII Supra?

Simple answer? You shouldn't. Period. They've been done before and they weren't anything more special than the 7m-gte.

Ugh. That sucks I have a 400 HP Motor and a blown 7mge in the supra now. If the tranny would fit up id just drop it in and get the mounts to fit it. I just want More powerful motor. And i dont want to fool with the 7mgte blowing head gaskets.

Then solve it, it's incredibly simple. Just do it right the first time.