Overheating at idle
What cam specs?
If not using one, use a
high flow 180 thermostat. At least remove & test the existing stat. It may not be opening fully.
Do not drill holes in the stat; all it does is increase warm up time.
Main problem is pump speed [ & therefore fan ] too slow; makes a BIG difference. Pump should be overdriven 10-20% relative to crank.
More info here:
www.stewartcomponents.com