1. 69-74, they have stronger blocks.But for the power you want most any 351W will do
2. A clevland is actualy considerd a big block, and I've head have cooling/oiling issues
3. I think they were carbed until 1990
4. I dont know, it depends on you, are you good at wiring and have experiance with efi systems?If not, then probably yes.
5. You might not even need to, it really depends on the manifold and carb used.
6. use same mounts as a 302.
7. Is it the trans that was on the 3.8?If it was I don't know, but it won't fit a 302 either if it is.
8. Hmm, not really sure, I think they use the same as the 302, but not sure because the motors have differnt balances.
if the you can switch the bellhousings on your 5 speed to make it fit a v8 if you need to. clevelands don't have cooling/oiling issues. that is a myth. only when you put remote oil filters and such is when people have problems.