Still trying to debug my 70 Darts brakes - for a recap KH disc from a 69 Cuda on the front, rear 10" drum. The master cyllinder I keep getting form the part stores is the same as for drum, same size reservoirs front and back. What would happen if I put on the 73 MC with larger front reservoir? Would it work, could I "blow out" a line or calliper?

It'd work. If manual brakes just confirm the circular recess is there in the rear piston "thimble" about halfway down. Too big of bore might make leg effort objectionable (less leverage) but I have a big bore (1&1/8") alum M/C on a 69 dart with KH sbp discs/10" drums & it stops excellent & you'll be fine

Thanks RR, I thought it wuld work, just wanted to be sure

You're welcome/much appreciated & good luck with your project