you need to measure the width of the shoe for the 11" drum 2" 2.5"
ask for b-body or c-body brakes 11x2.5 ect..
whats wrong with 11" brakes on the A-body?
I swaped my 68 dart to 73 manual disc with stock prop valve
used a 4 bolt to 2 bolt MP adapter,used the large diam 2 bolt alum mc,used the lagest wheel cyl for c-body 11"x2.5 drums on my 8 3/4 rear axle
even up it to the r-body 12" front disc and added the cooling tube to the splash sheild
never had a problem and it would stop very quik from high speeds