What fan clutch are you running ?
I might be inclined to try a fixed fan and see if it helps.
Vegas summers are brutal, it might just be the car has met its match.
I have the 7 blade metal stock replacement fan, I can't think of the part # right now but its one that was suggested on FABO. My clutch is just the stock replacement can clutch from Oreilys... nothing fancy.
I have a fan shroud... but the fan shroud is kind of sucky... It was one of the first things I got, but didn't realize that I actually needed an offset fan shroud for my engine (340 engine), so the shroud definitely has some openings at the top and the bottom of it.
I'll drain the radiator, replace the thermostat with a 180 (just in case) and add more coolant...
Vegas summers are Brutal, 100 degrees today and this summer we have actually been having record Temps. So many days of 110-120 degrees outside.