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
I have verified my 180 high flow stat is fully opening with the pot of water on the stove method prior to installing. I did some research on overdriven pulleys and found the only way to get anything overdriven was to change the entire pulley set up to serpentine like the CVF 1:20 set up as the stock overdriven pulleys are super hard to find. I figured I would try the stock non AC Pulley I had as that wasn't really in the budget at the time.