What donor axle for my 64?

[GMCMG]

I am two days into my 64 GMC half-ton build project, and have stripped it down to the cab, suspension, and frame. Once the cab is off, I am prepping the frame, and doing suspension/drivetrain. I am converting the front to disc brakes from a 78, and will have 5 lugs. I am looking for suggestions for a donor axle for the rear. I am looking for something that I can preferably bolt on, but am willing to cut/weld spring mounts as necessary. Here are my needs: 2.4 to 2.5 something ratio (was looking at 2.41), would like to match the wheel offsets on the 78 (believe it is a 62" axle, but correct me), don't care about posi or anything like that, will probably stick with drums, and stick with leaf springs. I would like to soften the rear suspension, as this truck will never haul anything, so would be interested in suggestions here, as well. Maybe a car axle/leafs?
Thanks in advance.