I'm coming in a little late, but I figure I'd share what I learned anyway.
I have a '69 which originally had A/C. I have installed a Griffin Universal 31" x 19" with 2 1 1/4" rows. Mine went in without any mounting modifications, but just different hoses. I have heard some later models had to relocate the upper brackets, so YMMV. I have part number is 1-55242-X (or GRI-1-55242-X for Summit). I bought it about 2 or 3 years ago and it was $260. Now it is $295. They also have the same radiator with 2 1" rows (GRI-1-25242-X) for $190.
Since I bought mine, I found out that the Griffin radiators use an epoxy core. Other bang for the buck options include the BeCool universal (BCI-65003, $290) and the Summit universal (SUM-380331, $180). These are both 2 1" rows, but use vacuum brazed radiator core which I have read is better.