Guys, excellent discussion re: the aluminum radiators. After reading this thread, I took my 3 core brass radiator to the local radiator shop that had been there for the past 18 years and had it recored for $90. A 2-year warranty left a warm feeling inside. The car never overheated here in Bakersfield, CA in 100F+, but I don't do any racing events.
Aluminum ebay radiators are like lottery - sometimes you hit a quality product, sometimes not. I wish local places like AFCO in IA can make aluminum radiators for our 280z's. I have their unit in my 67 Camaro and for 180$ this was a piece of welding art. It still has a sticker "Made in US" ('with pride').