Don, here's my 2c: my 54 1/2 ton daily driver (327/400) works just fine with reconditioned Pacer IFS from a junk yard. (A bolt-in on the 54 so it's an almost idiot-proof install--it needed to be!-- and the Chevy frame remains uncut.) I got HD coils from Eaton--you tell them the application and the ride height etc., they tell you the spring to spring for. So no spring rates probs. The Bendix discs are big and powerful and well up to the job, and the steering ratio is just right (through a Grant wheel on a tilt on mine).
Replacement parts reasonably priced and readily available for the whole shebang and it's very robust.
I don't know if Pacer is the best solution for a fifty thousand dollar 46 Panel--maybe someone who's been there will post if they can still afford a computer--but you mentioned it and that's my experience with it.
Good luck!
Christian
