Hi, been having issue of overheating, ok driving but around town and sitting still, temp rises up over 200 deg. I usually put in neutral and rev engine up a little to cool back down.. heres what I have, 68 firebird, 350 engine recently rebuilt, maybe a couple of thousand on engine now. slight cam, and intake edlebrock ,match, new 3 core radiator and water pump, new clutch fan, upgraded fan to 21 inch I believe.. have a shroud on but thinking of replacing, not a great fit... a friend told me about a plastic fan the dragracers use, and get rid of the clutch.. any other good info you like or that workks good.. thanks

There is a post below on engine heating on highway. Just about evetything in that post will apply to your situation aside from airflow problems. I would be suspicious of t-stat water pump clutch fan timing air fuel mixture,and possible tight engine.

I have a 400 coupe. Just got it put back together with a nearly 500 hp 455. Since the next step is paint, I have not installed any of the extra cooling parts for the 400 such as the upper and lower baffle plates or the plastic mastic pieces to channel flow straight into the radiator.

All I have is a custom 4 row aluminum radiator from Rodney Red, a stock 19 inch clutch fan and a OEM shroud.

Last weekend I was went to a local cruise-in down mid-town streets with 30 mph limits and lots of stop lights. Temps in the mid 90's and 60% humidity

My OEM Rally temp gauge never got above the 3/4 mark which is where it stops after the 190 thermostat opens

at idle after driving 'over 200 F' is not really that hot.....
if its at 225-230 after driving hard and then sitting at red light,yes its hot...and that wouldnt even be bad if in 'southern climates'....
remember the "idiot light" for over heating in these cars came on at 245 F IIRC ...

Did you try the water pump plate trick? Worked well for me and lots of other pontiac owners.