lots of things play into engine temps, including where you temp it at (head button or fins), ambient air temps, fuel types, glow plug choice etc. Don't worry about the slightly cool temp if the performance is good. If its smoking heavily and burbling around the track you might want to lean the High Speed Needle an 1/8 turn or so to see if that helps.
I've always been taught to tune the engine for performance and the temp is only a secondary check to see if you're too lean or otherwise way off.