Master cylinder

OK, I looked and they don't give the caliper piston size. I was just wondering as some conversions are for the 80's metric GM 1 piston calipers with 2-3/8" piston bore, and those are so small as to not give adequate front brake force. The pix the POL shosws LOOK like Mopar 1-piston calipers but it is really hard to tell.