Classic/Antique Car Repair: auto overheating, radiator shrouds, plymouth satellite

Question
I just bot a 1967 Plymouth satellite, had the engine completely rebuilt and now have overheat issues. There is a new water pump, thermostat, system flushed, overheats after driving for about half hour. I assume the head gasket should be fine. What are my next steps to solve this overheating? It has a 273 v-8 no AC. Recore radiator? Ad a shroud? Does not have one! Has original radiator.My mechanic is good but baffled. Thanks in advance.

Answer
Ok, have you pressure checked or replaced the radiator cap? These systems need to run under pressure. If the cap is Ok, I would suspect that the radiator is partially plugged. Flushing will not touch accumulated deposits in the radiator. The clue for the radiator problem is if the engine does not overheat at low speeds but the overheat becomes more severe as you drive faster. These engine did just fine without radiator shrouds when the were new so a shroud if it works will only mask the real problem.