Heartbeatcitycamaro can reproduce the origianl harrison copper radiators. This is the one they listed the closest for the UQ MT 400 radiator with OO and IL tanks. http://www.heartbeatcitycamaro.com/store/product/13514/Camaro-Harrison-Radiator-BB-MT-4C-CN-1969/ However it had the wrong upper neck for the Firebird. They do list other Radiators with the IL tank with the correct neck but this is the only one with the OO passenger tank.
So I called them and requested the same radiator but built with the IL driver side tank with straight upper neck. They did not have any issues building it the way I needed.
It took about 6-8 weeks to get it. I had it built using the UQ radiator specifications so it has OO passenger and IL driver tanks with the correct core, core channels and brackets.
It comes unpainted so you have to paint it yourself. I thought others may be interested in seeing a fresh build Harrison 4 core UQ radiator.