Issues with swapping out 250/3speed with 350/TH400

[BigRed]

Got a question for all the experts here. I currently have a '75 SWB Custom Deluxe 1/2 ton 2wd that originally had a 250/3 speed - column shift and was converted to a 350/TH400 at some time. Anyway, I will be getting another '75 that is a LWB with the same setup (250/3speed). Since the body on my truck is pretty eaten up with rust, I'm thinking of swapping my engine and Tranny out and putting them in the LWB.

Can anyone give me some info of possible issues and complications with this. As you can figure out, I already have an auto column on my current truck to put in new one and any mounts, etc. The one problem I can think of is the driveshaft. Will I be able to keep the existing drive shaft on the LWB or will I have to find a new one?

Basically, I'm trying to decide if I should replace my cab and body parts with that donor truck or would it be easier to put my engine and tranny into that truck?

Thanks for everyone's help!!!