Float level
I've used the method of having fuel seep out of the pilot jet. It worked OK, but what gives me pause for thought is that on a GP, Amal actually specify where the float level should be, and it is at the bottom of the 1/4" circle inscribed concentrically with the pilot jet. This suggests that the level should be 1/8" BELOW the pilot jet.
On the event, I used suck-it-and-see on the front carb of the twin, and while it is notoriously difficult to evaluate one's own brainwaves objectively, there was a noticeable improvement in the smoothness of the motor, AND visible evidence on the plug (traces of dark brown) that it was less rich than before.
Just as "calibration" the plug on my Manx is best described as "dirty white", whereas the rear pot of the Vin is light brown. Race bikes of course spend much of their time at full throttle, but there are many who believe that one should just "lean it out until it "pops" on the over-run", then either take the chance and leave it, or richen it one. (I used an exhaust sniffer.) Whatever, the plugs are usually virtually white, and the inside of the mega grey.