Is this stuff interchangable?

[rzarock]

It's a long story, but here goes. I'm rebuilding a 77 Silverado short bed and have an opportunity to purchase an 84 K20 4X4 with a 6.2L diesel. The K20 runs and is in relatively good shape. The owner wants $1500 obo. I've been looking for a 6.2L diesel to put in the 77 (I run biodiesel) and thought it would be nice if I could transplant the drive train from the 84 into the 77. The 77 is an automatic...the 84 is a 4 speed manual, which I prefer. Here's the question: If I transplant the drive train could I also swap the cab/doors and expect the doghouse and bed to line up? I like the look of the 77 front end over the 84 and want to keep it. I also need a tailgate. Could I use the one from the 84? Would an 84 bench seat fit in the 77? Thanks for all your help!

You can check out the build process at:
http://www.cardomain.com/ride/2931839