[Pontirag]

your running a flex fan and no shroud? thats part of the problem. A hotter cam in a low compression motor, thats part of the problem.

later cars runn hotter because its engineered that way to assist in emmissions polution controls so thats not relevent.

you replaced the pump and the radiator but did you flush the engine cooling system at all? and at any point did you drain the cooling system and let all the rust,scales and debri inside the cooling system dry out befor you reinstalled the antifreez? taht stuff when its dry's out becomes hard as cement and almost no amount of flushing will remove it. Thats a no no. Too bad you replaced the water pump and radiator as I would recomend putting a little draino in the water and running it up to temperature befor flushing the system. Draino is very bad for water pumps and radiators but its effective on rustand stuff like that. a little red nechish but it works. But I cant recomend it after you installed a new rd and pump.

Rethink the cam and check your entire ignition system from the balancer to the vacuum advance and mechanical advance. If you installed new plugs of the same heat range that should not be the problem but if you changed the range that could be part of the problem. Also with the hotter cam in a smog motor do you know the condition of your cylinder heads in terms of oil usage and carbon build up? all of these are factors.

326 3 core radiator should be able to handle what you got , especially cleaned out. Other posts are talkin rebuilt this and that but Idid not see that in your first post. hot cam in a 30 year old motor is askin alot. what did you do to the carb to compensate for these changes? Dual exauste on a smog motor will cause it to rune a bit too lean , more so with the hotter cam