Thanks 3B and Grigg.
I got truck in running condition, but no brakesm even park brake worn out. Rear looks to be recently redone, front no signs of leaks and lots of shoe left. MC was empty and cap seized, brake June from it to hydrovac replaced.
My first debate is changing to a dual circuit... problem there is first what to use, need 17500lb ability to match chassis. But to complicate things, in this firebolt at least, the MC is reverse mounted to allow a second clutch linkage from the pump,greatly reducing area to work in. Don't really want to need two boosters , one per circuit.
So then if I stay original.. without tearing mine apart can I tell bore size as no tags or cast numbers are on it (to get proper rebuild kit), is an 1 1/4 bore the largest offered? 3B the Napa one has mounts wrong side (assuming they're the bolt bosses in puck not outlets), both talk of two outlets. Mine only has one at the end opposite the pushrod.