I'm much more concerned about the temperature of the valves (giving adequate cooling to the exhaust seats) and that the cylinder head is iron and more likely to retain heat and have hot spots versus the piston that is aluminum and will better distribute the heat through the whole piston and be less prone to hot spotting. If my tune and EGT's are in control, I won't be overly concerned about piston temps.
I don't run any kind of restrictor or thermostat in the cooling system, so speed should be relatively good. The coolant passages in the head deck are between the cylinders and don't appear to have any special direction to them. I intentionally went with two inlets into the head to try and create pressure in the head to keep the typically hot spots around the exhaust ports from boiling, which of course is to keep cooling the exhaust valve. I eventually plan on having a 55gpm water pump on it, so should be able to set the engine temp where ever I want it to be on most days, if I feel I need lower bore temperatures, then the head would just be lower, and that wouldn't be a bad thing. I already have it programmed to run full flow, regardless of engine temp, when ever the engine load is medium to high (above 60kPa MAP, or 70%TPS) and that will work even better with the 55gpm pump.
