Glen-Ray would be the place.

What are you trying to cool?Do you have original brass tanks? It's hard to beat the efficiency of an aluminum core with a copper brass core. Copper brass is considerably more expensive now. I would take a good quality copper brass if originality and exact fit is a concern too.

Been in the radiator business for 35 years and my advice it that if you have good solid original tanks, take it to a radiator shop and have them recore it with a QUALITY high efficiency core with 5/8 tubes on a 3/8 center and around 14 fins per inch if you are not pushing the horsepower limits.

Reason I say quality is that just like everything else, there are good and bad core mfgs out there too. And the good ones are becoming fewer and fewer due to everyone wanting cheap.

So are you OK with an aluminum or no? Aluminum will always be the most efficient due to the way the fins are attached to the tubes.

I have looked at those Glenn Ray radiators before. $1400 seems like a lot but for me to recore a BB B body radiator with a high efficiency core like I described above would be close to 1100 I bet. The original Big Block B Body radiators were 3 Rows of 5/8 tubes on 9/16 centers. That core had around an 80 percent thermal efficiency. If you have that core made on 3/8 tube centers, you get 23 more tubes per row, which means you almost have as many tubes as the original if it was a 4 row, and the thermal efficiency goes over 90 percent. Its the most efficient factory sized radiator you can make IMO.

Don't waste your time with any 1/2" tube radiator core or anything that has a tube center over 9/16"......

They work fine for grandmas valiant with a slant 6 in it, but not for anything performance minded.