Another overheating situation 63 Slant six

Rats thought Id gotten all my data down. Sigh.
The car is a 63 Dart convertible with a 225 SS. It has a mild cam installed, it was bored .060 and the head milled .0100 or so. The cam was degreed in ok. It has the Super six dual barrel carb added.
The water pump was replaced last fall as the old one was squealing like a stuck pig.
The car will overheat when I run it up to speed and climb as I get up to speed. As I said in the post it heats up so quickly I cant really get going too long. I live in a subdivision and there is a stretch of road behind the high school where I can get up to 40 or so and by the time I go the less than two miles, it is going up and up. It seemed to run about 180 for a while at the beginning, about 30 mph. As I hit the back road and punched it to put a load on the motor it began to climb up to 200 the 220 and Im easing back home limping slowly.
I will take it out tomorrow, to see if I can better get a handle on the speed and how it heats up.
As far as the original radiator, I dont really have a place I have found in my area to get the original radiator recored and renewed.
Water pump pulley is stock, new belt, tight. At idle with the radiator cap off there is a ton of flow visible.
Thanks for the help yall.