Martin, I'm running a copper radiator with tranny cooler in the bottom on my 52 panel. Its a 4 row desert cooler I purchased from JimCarter back around 2009....before copper prices went out of sight. I'm running small block with 700R4 and have never had one minute of trouble. I am also running a full cover electric fan which is great.
I ask Jim before I purchased it and at that time the radiator I got was made by U.S. Radiator.
For the price of a copper radiator today I think I'd go with aluminum which should also get the job done. It can be 4 row or 2 row.....it all depends on the size of the "flues" some run 1/2" some are even 1" and how far apart they are also determines how much they cool.
Good luck.
EDIT: Lots of radiator info here.
http://www.usradiator.com/cores
