Finally managed to find what looks like the correct radiator. I've got that coming, as well as the (hopefully) correct trailing arm, and a gasket for the new to me throttle body. I did plug the new one into the harness, clear the codes, and re-check it. First time I haven't seen the check engine light on in the car, so that's EXTREMELY promising.
It's looking like I should be able to enjoy the end of summer, and all of autumn, with the little convertible. Finally.