Caliper info needed

[rustyATV]

I'm looking for some info on the rear brake calipers for the below cars. By any chance, does anyone know, or know where I can find, the weights and piston diameters of them?

I'm trying to come up with a rear disc conversion for my truck and need a hydra-mechanical rear caliper like these cars have.

Honda S2000
Acura RSX
Late 80's to mid 90's RX7

Thanks!

[rustyATV]

Perhaps, is there someone with one of the above cars that's planning on putting on a new set of pads that can let me run down there with a scale while they're unbolted?

Might just have to pick a brand and go with it.