try timing the fuel flow through the carb.  Take the bowl off and time how fast the fuel flows through the needle and seat.

I thought about that Carl.... sounds messy   I guess if your serious, you could have the carb sitting next to the fuel tank and do a true measurement.  I wonder what flow rate is required for HRD builds.... I know this came up as a question before, but I don't remember if we ever got a final answer