With the genuine fuel filter, and other bits, quickly delivered from International Moto Parts, and the aftermarket pump from Axiom Performance, I was ready to get back some of the lost power.
So, tank up and fuel line disconnected, I thought I'd try another fuel flow test. No fuel runs out of the tank at all when I disconnect the pipe - which isn't right, it should flow out under gravity. This time, instead of connecting up a separate loom to the pump wiring, I'm just going to turn the ignition on and let the bike run its own priming cycle. That way I can compare fuel amounts before the work, and after.