Pick up a Laser Temp Gun and carry it with you whenever towing or boating. Use it to find bad bearings, brakes, tires (will be hotter than the rest) when towing, and use it when boating to validate your gauges and also find hot cylinders if you have trouble. Priceless investment.

what temp should a 500efi run at? mine is running around 150ish ,no higher

Well now mine is usually at 160 but sometimes will hit 180 and then it seems the thermostat opens up and rapidly drops down back to 150. I have a laser thermometer and will def compare it to my gauges thnx. Good idea!

Your fine, You should be running a 140 degree thermostat and a lot of times the gauge will show 10-15 degrees more then what the thermostat degrees is.