As long as you're using the harness from the 87 RX7 ZP4 thats the best harness to use as you only need to rewire the injectors as the rx7 runs 4 wires and the mx6 runs 2. If you know what you're doing this is a 2 min job.
All of my info on rewiring the harness came from the real hks mx6 harness. If you need a eprom chip let me know I still have a few.
I found its better to run a stock chip with only fc as apposed to using the fcd.
I have no idea what I'm doing, wish I had a real harness to refer to but I'm glad I've got you. And yes I do need the chips.
Are you saying run the PFC Fcon with chip and not using the Fuel Cut Defender?
Here are the two harnesses I have that are supposed to be from an RX7;
I have 2 PFC FCons, 2 GCC and 2 FCD (one old and one new) and one Mixture Cont.