Well the low float is very likely the cause of the pinging; every carb circuit (except maybe the accelerator pump) will be lean. 2/32" low is a fairly significant amount for a float to be low. The 1920 float can be checked via the wet float method without taking the carb off but changing the float setting does require the bowl to be removed. Not sure why to NOT find a gasket to change the float setting and get to this.
Checking the timing marks is like any other engine.... use the piston stop method to find true TDC on #1 and see where the 0 mark lies in relation to that.