Going from a straight 6 to a V8 in a 4x4

[FlameOut]

I recently purchased a 72 K10 SWB 3 speed manual (column shift) and wanted to replace the straight 6 with a sb 350. I've been reading where some say you need to replace the crossmember and some say you don't. But these are all 2wd I was reading about, so I'm not sure if being a 4wd will cause even more problems.

Will I be able to use an aluminum bellhousing in place of the cast iron one? At first I thought this was going to be a fairly easy swap, but now I'm thinking it will be more like a nightmare. I'm kind of getting to the point where I think I should just take my losses and scrap the truck. It needs just about everything but the bed repaired. My main project will be this engine swap, and if it's doable, I'll go one step at a time restoring this thing

Bill