I have a 69 ,396 ,4spd ,with a slightly radical cam , not sure what temp stat , but it runs around 180-190 , the radiator looks a little rusty on the lower 1/4 of the tank & fins , any suggestions what type of radiator to use ?

 

Remove radiator and have a rad shop recore it.
Second choice, get another brass/copper radiator like OE.
Third, get an alum core rad with plastic tanks and pray a tank seam doesn't leak/break.

 

Thanks for for info , So , the 100% radiators are not the real deal ?

 

Look at Cold Case radiators.

A BB motor 1st gen, or small block with AC, came with the 23" core vs the smaller 21". They both fit

You can take your radiator to a shop if you can find one that actually boils and rebuilds old copper radiators.

 

Cheapest and easiest path is to re-core the existing radiator. All aluminum radiators are not created equal.