Originally Posted by Howard Coleman CPR
relocating the front brakes to the rear would throw the balance out of kilter and you would end up around 50/50 and swap ends.
Oh if only he were enlarging the front brakes at the same time....
The RX-7 calipers seem pretty small, the pistons are, what, 38mm? Same piston area as the single-pot front units used since 1979 to the end of the FCs. So proper motorsports calipers up front with larger or more pistons should even things out (or vice-versa - the OE front calipers on the rear will re-establish balance).
RX-7 front calipers on the rear is a not uncommon thing to do for some club-level motorsports. Now you know why the calipers seem to be gone if you find an RX-7 in a junkyard.