I'm having similar high temp issues. I am running 68 w/ 350. Radiator shop shows my radiator as correct, flushed radiator and still pushing 210 - 240 degrees.
Any other areas I should be looking at? Any possibility that there might be a problem with motor?
When engine was rebuilt, evidently they forgot it was a 350 Pontiac and put it back together as a Chevy, forgot to put in the oil plug at rear of motor. I installed plug and got oil pumping to the lifters.
Is there another area I might check out?
Did you do all the other things I did? filler panels etc? the biggest seems to be getting the Fan shroud. Or go with electric fans which "knock on wood" seem to be helping me at idle.
