Rotor size

[barney911rs]

I wonder if someone can answer my question. I'm using the front caliper from a 77 320i on the rear of my early 911. With my limited BMW knowledge, I understand this was the only year that used a vented front rotor.

It fits fine, and has been working well, but I want to find out what the thickness was of the stock BMW rotor was. My rears are 20mm, and I want to see if I can fit the newer 24mm rotor in that caliper. Also does anyone have a source for a good race brake pad for that application. Thanks guys.