Over Heating

WHERE IS the timing and what is the timing curve? Make sure that is within reason

Determine what the fuel mixture is doing. If you don't have wideband, learn to read plugs, which is not a cure all

Change the thermostat "just because" to a Stant 180

Check out the water pump, belts as best you can

AND THEN

You have access to a high speed road nearby, one that you can get to fairly easily from your house? If so, remove the entire electric fan package and make a test run at least 45 mph and see if it overheats at that speed. If it does not the electric fans are not flowing enough air AND they are restricting free airflow at highway speed.

Or---as recommended above, get back to a factory fan setup. NOT a flex fan, and you want a shroud, which you can build. If nothing else, have a sheet metal shop build a blank pan, and then you do the rest.