Bob I simply took a piece of 090 aluminum and bent it 90* to hold my radiator in place. I bolted it to the core support and used the stock upper radiator pads. It looks like a typical radiator cover. I even used it to hold the top of my electrical fans in place since I'm using the 4th gen fans. No issues with it moving around. I haven't pushed my car as hard as you have though. I don't see it becoming a problem though. Good luck getting the radiator in. Hope it works well for you.
Here's a picture
