3/4 ton 4x4 auto trans

[Bones72Super]

I recently bought a 72 GMC K2500.It has a 350/th350 combo but reverse is out on the trans and I was thinking of putting an Overdrive trans in its place. Today while I was at the junkyard I found a 1994 3500 4x4 truck with 6.5 turbo diesel and what I think is a 4L80E.

My question is can I put the 4L80E behind the 350 and still use the 205 that's in the GMC or should I use the transfer case thats on the 4L80E.

I also have at my home a 94 tbi350/4L80E combo in my 72 suburban that was wrecked in 2011.It has the Howell swap harness and trans controller from the 94 GMC van I pulled the eng/trans combo from.Is there a way I can adapt that 2WD 4L80E to the 205.Since I already have that entire swap ready to go that would be easier a alot less expensive.

Thanks in advance, I am a complete noob to the 4WD game and any help steering me in the right direction would be greatly appreciated