I recently discovered the wiring to the radio in the RX7 to be pretty badly hacked up, so I put it back to stock, and made a missing piece of the harness to send signal to the amp for the rear speakers (the hack-job had the rear speakers spliced in parallel with the front...) and generally cleaned up the installation (including reconnecting a couple cut ground wires). I also cleaned the tape deck/heads and the volume pot, which made awful noises when turned. The black bin was also just flopping around, so I fixed its mount and secured it, too.
I’m pleased to report that, while the tape deck and AM radio is still dead, FM works miles better than it ever has (great reception, even in the garage), the fade/balance works correctly, the volume knob works without noise, and it sounds really good. The only thing non-stock are the speakers themselves, and they’re pretty nice 2-way pioneers so I’m not concerned there.
I’m in the process of trying to get the stack out of a GSL-SE, which would have a digital tuner in place of the analog as well as a (hopefully) functional tape deck and an 80's-tastic graphic EQ where I have the little half-DIN bin. As a bonus, it has better and higher-wattage amps.
Now if the weather would ever stop being so shitty...