Upgrade front brakes

OK. So that confirms its a distribution block combination safety switch with proportioning valve.
It looks like they have some mopar options, in fact the ones for a '73 a-body. I don't know what the difference is, if any, in the proportioning or the light. Might ask them tommorrow.
https://www.getdiscbrakes.com/brakes/proportioning-valves-and-blocks?product_list_limit=52

If you're getting full pressure on the front calipers (and the rears) then I'd try pads with more initial bite. I'm not sure what is available for the brake. I know for my Wagoneer, Raybestos had a pad "Profession Grade" semi-metalic (M at the end pad number) that I found very grippy. Lining has FF friction rating too, which is decent for street pad.