Sorry for the tardy reply eastbaysolo (three months).
Although my 510 has an SR20, I figure for posterity I could contribute on the off hand chance someone searches this up. BTW I'm in the East Bay as well so maybe we can check out each other's cars some day.
I have a Ron Davis rad that I got from Mckinney Motorsports 8 years ago and I think I paid $500 for it. Honestly, I'm not sure it's the same one the OP is talking about, but I'll post some picts of mine. I recall having to rotate the lower hose 90 degrees lining it up with the inlet on the SR20. I have never had an issue with the rad nor has it overheated. Bare in mind though, there are a lot of variable that can contribute to the running temp of a car. I have a super high CFM 12" electric fan with 16 wide cowl and the rad is mounted right up against the intercooler so there's very little blow by out the sides. On a turbocharged engine, one of the biggest factors in heat build up is pushing a smaller turbo passed it's ideal efficiency range. There is an advantage in getting quicker spool up, but heat and controllability are the down side. Part of the reason my car runs cool is I have a GT3071r at 15psi getting 300 rwhp running e85. For safety sake the fuel mixture is set towards the rich side so that also helps cool it. Obvious down side of a bigger turbo is slow spool up, but the throttle control is so crisp and linear it makes it easier to keep the motor revved and all boosted up so the power is instantly accessible.
I've talked to a guy who has this same Ron Davis rad on as me on his SR and he's experienced over heating. But he is pushing a T28 to it's outer limits over 18 psi chasing max HP. He's also running a stage 1 cam on 91 oct pump gas. He claims 385hp but I'm dubious.
Sometimes people loose touch with subjectivity, because they've got they're heads stuck too far up they're own,,, Reality.