best AFR gauge setup

Auto Meter makes a stand-alone gauge. Most are driven by digital stepper motors because generally wide band 02 sensors are three wire and use a 5v reference voltage.
WOT you want 12.5-13:1. Some will say 11:1 to be safe but IMO that’s just wasting fuel. Any higher than 13:1 is not enough fuel in the mixture to make power.