I have a pusher and puller fans and together they move 3,000 CF: part of the puzzle? Wonder if it would be possible to put a smaller pulley on the water pump because idling is worse but at temp's of 100+ here in Phoenix it may not be much help?
I HOPE for your sake its just a crap radiator issue. Get a GOOD COPPER radiator if you can afford it. I run my rehabilitated 1965 Mopar 2524984, which does so well that I happily jumped at the chance to get another one from Florida for $300, then had the same shop rod and seal it. I ran just my FFD fan on it from December through April, 5 months, then bolted my 7 blade Mopar 2863215 18 inch fan onto the water pump for the hot season in Toostoned. I got a shroud w the deal in Florida, and yes, it helps pull a bit more air through, though I would nver have bought it without that primo old radiator attached.
Dollar for dollar, if I were to get an aluminum radiator again, I'd go to ECP and have them build one if they don't have one ready. I used one on Mathilda with good results until it got destroyed, but it cooled very well. Again, I ran a pusher and had built a custom box shroud for that one, which helped the mech fan in the summer.
I run a non-AC pump on my 383 now, with good results, and use a 180F RobertShaw thermostat. THOSE HELP! All thermostats are NOT created equal man. Like you, I've thought about using a smaller pully with the more common sorts of after market pump, but with a rebuilt old school non-AC one, I stick w the pully meant for those.
I suspect your radiator and thermostat aren't up to the job. Phx does get seriously hot, so I reckon you best fix this. Maybe a Flowkooler pump will do you good too. If I didn't have a nice horde of Old School non-AC pumps now, I'd try one of those.