I have had really good luck with the cheap Summit Racing aluminum radiators. They are about 200 bucks, and one of them cools my Galaxie like a dream. I had one in my Mach 1 too, when I was running the 511" medium riser engine, and it also cooled well. I had to notch the frame rails of the Mach 1 to get the 19 X 31 radiator to fit, though.
I don't particularly care for Griffins because they use epoxy to help seal the core to the tanks. If you are going to spend that much on a radiator it ought to be fully welded in my opinion. For my Mach 1 with the supercharged engine (which was a big challenge to cool), and also for my Shelby clone, I ordered custom radiators from C&R racing in Indianapolis. They do a lot of NASCAR stuff, and they can make whatever sized and thickness core you want. Really good products, IMO, and about the same price as a Griffin.
http://www.crracing.com/