NM51,
I went through this same debate with myself over my solid-axle '59 Apache. I decided to reproduce the original GM power steering, optional on these trucks. This PS is a 'linkage' type that is 'added on' to the stock components. You can get new or used C-2 or C-3 Corvette components to duplicate the same setup. Mine works just fine.
If you mount a R&P to your axle, make sure you have the clearance between the steering column and the PS input as it moves up and down. The guys who tell you that a frame mount will produce 'bump-steer' are right.
You're going to have all manner of 'vibration feedback' with the R&P moving up and down with the axle using a slip-shaft to the steering column. Yeah, the wheels could just exactly cancel each other out as the axle moves, but that doesn't always happen.
