Thermostat or not

I always run a balanced thermostat but if I couldn't I would not run without at least a restrictor in there. Gages can show cool temps as the coolant is exiting the intake but the it may not be picking up as much heat as it should be if it's moved through the block (pumps) too fast. If your temp gage shows cool (like 160-180) but a temp gun shows hotter (usually 200+) when aimed at the core plugs on the end of the heads, that could be the issue.