Last year we put '96 5 litre Mustang heads on an early 302 block out of a Torino. It isn't used often but seemed ok though it ran hotter. Now it's pulling coolant out of the overflow every run. Pressure check holds, laser gun shows normal temps, thermostat is new, 180 fail open, no foam or brown in the engine oil....So, mini head gasket leak? is there a steam hole issue with sbf engines?? Ideas?? Thanks, Al D