I have done a couple of Dana 60 rears from truck rears. The only difference worth mentioning is the lack of the pinion snubber mount on the truck rear. That may have been some value when the only traction aid in common use was the Super Stock Springs and not worth paying a premium for an OEM housing

The truck Danas have very thick tube walls which should be welded to the cast steel centers with 7018 rod after deep cleaning the joint. As to the finished width of the rear, first assemble the wheels and tires you want to use and roll them under the vehicle less the axle. Center them in the wheel wells, measure the distance between the wheel mounting surfaces and subtract the thickness of brake drums or rotors. That will be the overall width of the rear, flange to flange. If you use leaf springs you will need to be careful with wheel back spacing to avoid interference, DAMHIK! I won't use Mopar ends on a custom rear again. Use the big Ford housing ends and you can use sealed bearings that you don't have to pack. Lots of sources for 35 spline axles including Dr. Diff. OEM axle shafts are weaker(fewer splines). Take the pieces to a 4x4 shop or someone with a jig and have it welded up straight.