Need opinions on 66 Chevy 3/4 frame disc swap questions...

[GMCMG]

I have read every FAQ and thread I can find, and still don't have enough information to answer these questions without input from people who know better.

A brief summary of my build to add context to my question: I am building a 64 GMC 1/2 ton LWB on a 66 Chevy 3/4 ton frame, so I have trailing arms for the air ride setup. I have a 62 GMC donor truck that was converted by the PO to front discs/5 lugs using front parts/rear axle from a 78. I want to convert the 66 3/4 ton frame to disc/5 lug using parts from the 62 (which is at this time a complete truck). I want to make this as easy as possible/do it right, keeping in mind that I will be working around body/engine on the 62.

Questions: should I swap the entire front cross member, or parts? If just parts, which ones? If the entire cross member, does anyone have any good suggestions for easy ways to get to the crossmember bolts without taking everything apart? I don't mind pulling the engine out of the 62 - I have a friend that wants it anyway. Any other bright ideas/something I might not have thought of/etc. would be appreciated. This is my first attempt at something like this, and I don't want to screw it up or generate more work for myself than I have to. Any and all input is greatly appreciated. Thanks!