There is a Power FC for the 300zx, I think it's just a modified skyline unit. Most people would recommend a Microtech. The standard 300zx ECU can also be chipped and retuned.
Yep, UAS are the only shop I know of in the world that does them. Modified R33GTR unit. IMHO the only benefit is most tuners know them inside out. Go a microtec or retune the standard ecu.
And the price. And it's not really a proper standalone ECU, just a fancy chipped 33 ECU, although the MAP sensor version is a bit better.