Water Pump

not an engineer but a smaller pully increases water pump shaft speed but I'm sure the vane design (spiral vanes /pushing water vs paddles/slapping water) / backing plate and clearances eliminate cavitation... The coolant itself is also a factor. ie thermo clutch/fan /shroud/radiator... Just dumping the 50 yr old 340 fan clutch and installing a hayden HD 90 % fan clutch made a HUGE difference in my application... Being you have a condenser in front of your radiator I would be also looking at air flow /fan /shroud/hood seal ect

I won't even get into timing with the crap gas. That can affect engine temp

The thing I have learned here ITS THE WHOLE package /my engine runs at 190 anywhere!!