Had time tonight to look into the clutch setup. There are various 1"x 23 spline clutches from Dodge in the 70s. Found a 12" from the 75 W200, and 10.5" and 11" from the 77 Ramcharger. The standard bolts on the Cummins flywheel for "stock" clutches are at 12.5" diameter. Seems a little tight to get the 12" in there, but maybe. No local parts store has a 12" kit in stock to try. Chad mentioned the 11" HD kit from OReillys. I tracked that back to part number K1877-06HD. That crosses with K1877-06, MU5505-1B (alternate NU5551-3), NCF 1105016 at various retailers in non-HD form. There is a Duralast kit in town at an Autozone (NU5551-3) that I may go look at. I'd have to order the specific HD kit, none local.
Doug, do you know why the non HD's don't fit according to Chad? I see several different pressure plate designs across those part numbers so that's my only thought without having them hands on. But Chad posted pictures on his company facebook page that have the thickest of the plates (at outer edge)... so I'm confused. It's no big deal to stick to the one kit, but if there are options it would be good to know.
The clutch fork/slave parts all appear to be from the 96-08 Dodge Ram. That slave is huge!