You can buy a stock replacement for around 100 bucks that is a one row aluminum with plastic side tanks. The one row aluminum is supposed to flow way better than a 3 row brass. Lots of guys were using stock replacement F-body radiators to take advantage of this, but you had to bend the transmission lines to fit. Now direct fit aluminum/plastic rads are widely available for g-bodies. I know some guys hate the look of a plastic tank rad, but I've personally had horrible luck with cheap replacement brass rads, so my next one will be plastic/aluminum.
Something to think about - if you car is all original, don't throw away your original radiator. As our cars get older, people are going to start paying attention to originality, and will want date coded correct original parts. Having a factory rad with the right labels and stuff might be important some day. Just my 2 cents.