At about 60 inches lots of rear axles are about that width. My AD has a 62 inch wide rear under it currently that came from under a Chevelle wagon. If you measure a late 50's early 60's pickup you may find they are close enough. Wheel size and offset, tire size, and ride height all play into knowing exactly what size is going to work.
Your motor might be a limiting factor running on today's roads. With a rear axle change and T-5 I think you can get it to run highway speeds, but that motor isn't one I'd be comfortable spinning fast for extended periods.
As for the front, its possible you don't need to do anything. Are the kingpins and bearings good? If so you may be able to get away with jut running it. How are the brakes?
