Classic Industries, as an example, on page 660 of their current on line 67-69 Camaro catalog, lists 12 small block and 15 big block applications. Prices for SB radiators vary from $220 to $275; BB radiators vary from $270 to $320.
That would be the way I would go, and did a couple of years ago, when I purchased a replacement radiator for my '69 RS from Classic Industries. The original radiator now is on display hanging on the garage wall. I am not a big fan of trying to recore old radiators - at least in my experience it usually is not the best $$$ investment. Just my two cents.