Recently bought a '72 2002 that ran hot, temp gauge near red, so I replaced thermostat with no improvement. Went ahead and removed radiator and took it to local radiator shop. The guy took one look inside and said it was 90 % blocked and needed to be rodded out. I said okay and left it with him, but he called me later that day and said I had some corrosion along the bottom and it should be re-cored. He went on to explain that the radiator had 3 rows of 1/4 inch tube but he couldn't get 1/4 inch tube any more but that he could install 2 rows of 5/8 inch tube and I would have better cooling. Since cooling capacity is related to surface area, and surface area varies with the square of the radius, I did some quick calculations and figured he may be right, so I said go ahead.
The rest of the story is that the car now runs very cool, temp gauge hardly ever makes it to the halfway point, even sitting in Dallas traffic on a hot afternoon. The guy charged my $300 but I couldn't be more pleased.