I went from a 351 to a 395 stroker, and I am finding that I am running a little hot. I switched from a 20" radiator to a 24" radiator years ago, can't remember if it was 2 or 3 row. It still wont keep up.
i have a 3 core 24" with a clutch fan and shroud and don't have any heating problems. I did, however have the rad rebuilt at a local shop and the tubes were much bigger than what was originally in the aftermarket repro rad i had. i ended up using a stock top tank and the repro bottom tank but that was purely for aesthetics. i would say go to a 3 row but have it built locally instead of buying a repro. overall i would say the tubes were probably around 1/8" wider and deeper as well.