I see where you cut out the old gauge face. How much of a lip did you leave for the new inlay to glue to? It sets in from the front, or the rear of the panel?
I can answer one of your questions. WMS is wheel mounting surface. This is a measurement used in defining width of axle. Slide your rim on the studs and when it stops, it hit the WMS for that side.
looking for a complete bolt on disc brake kit off a later mopar with the big bolt pattern. Gave up on sourcing locally, however the closer to TX, the better, to save on shipping.