383 or 400 ?

HECK yeah. What he said. ^^^^^^^

IMHO, I think folks make too much ado about the 400's compression. Yeah, it's dismal, but you still have 400 kyoobs. It's GONNA make power as long as you do some good head work and put a good induction and exhaust on it. and look at what you'll have. A snappy engine that'll run all day on 87 and never say one word.

The problem is when people put a big cam in and wonder why it has soggy low end torque. If you stick with muscle and rv type cams it runs just fine.