Here is a side view of a piston/caliper.
This one is from 1959-1972, yours might be very close to same specs.
There is an inner seal no.3, the big rubber part is probably the dust cover (pic from "WorldPac"/fastlane)
I'm just showing the inside of a caliper, nothing else.......
BTW, I to have to decide on "doing" the kit or reman.....
The difference? $15 or $70 .... Lets say that I don't have cash coming out of my "Wasoo"