I have a 22 inch aluminum radiator in my '65 Coronet and I have a 512 inch big block with a 7 blade mechanical fan. I use a Mopar aluminum water pump housing. So my combo is pretty close to the OP. My engine gets up to 180 degrees (I have a 180 thermostat) and then it just stays there. I can idle for 20 minutes on a hot day and it doesn't go above 180 or 185. I can drive at low speed, freeway speed, etc and it stays right around 180. My Sniper EFI system has a data logger so I can drive around town and then look at the coolant temp to see what the log says.