Champion radiator for ~500hp small block??

No disagreement here. But it's hard to complain about a $200 radiator not being a perfect fit in this day and age, there are far more expensive radiators that don't fit any better.

I'm not saying it's right, but I think to get factory level fit you'd need to have a factory radiator re-cored. And you can't do that for $200 anymore either.
I know, right? Just price one with US Radiator and you'll begin to appreciate Champion. lol