Ok so I finally picked a radiator for my project, it's a tranmission cooler to be exact. They are made by B&M and come native with 1/2" fittings, so no soldering needed. Plus all are high efficiency. Until i get mine next week I can only speculate on performance but the specs seem to be better than heater cores, and plus the sizes for the ones I posted are all capable of using 2 120mm fans.
My Model (The one I got)
SuperCooler 24,000 GVW 11"x6"x1-1/2" Part# 70264
http://www.atlanticspeed.com/store/superCooler.jpg
Bought this one for $57
also the other models that seem to be pretty good are.
#70266
SuperCooler 28,000 GVW 11"x8"x1-1/2"
About $70
#70273
SuperCooler 15,000 BTU 11"x5-3/4"x1-1/2"
About $65
PRICES INCLUDE SHIPPING!!!!! ALL ARE WEB PRICES
look here is interested
http://www.atlanticspeed.com/store/B...%20Coolers.asp