Would an LS1 crate engine be better for power and driveability than the original engine beefed up, or and carbeurated crate engine for that matter? Secondly, would an LS1 bolt right up to a turbo 400 tranny?

 

An 81 Z28 is going to have an origional Chevy small block, unfortunately for you, the LS1 is not based off of the origional small block design, so unless you do significant modification, you aren't going to be able to mount it correctly. I don't know about your transmission problem, but if the motor doesn't fit, I don't think it really matters if the tranny bolts up or not.

 

LS1 would beat both, most definitely.

I think you can drop into thirdgen.org and find at least a handful of LS1 swappers to take notes from...