My motor runs cool....maybe too cool?

The stat sets the minimum operating temp, by closing ..... to get the temperature up. Once it is wide open, it cannot do anything more, it has done all that it can do.
The maximum temperature of your system will be governed by the efficiency of your system.
If your system has say a 180 stat in it, that is known to be in good working order, and it won't come up to temp; here are some possibilities;
1) the engine is running pig-rich and/or with retarded timing and a lot of the heat is going into the exhaust, or
2) you have a high-efficiency fan, running full time. or
3) the hood is open
4) the alloy heads do suck a lotta heat out of the water; I painted mine several coats of engine enamel
5) at idle the engine only has to produce enough power to idle! no surprise there. That might be FIVE horsepower So how hot can it get? It wouldn't surprise me at all if the stat closed up most of the way, and the water was mostly going thru the bypass. But if the stat is defective or missing, well the water is gonna go thru the rad instead of shortcutting back to the inlet via the bypass.
6) don't forget, your temp sensor has to not only be in the water, but in flowing water, NOT in a stagnant pocket created by two or more adapters, with the adapters radiating their heat into the airflow of the fan.