G'Day Pat, thanks for that mate, it was the blocked vent pipe that caused the flooding, I stuck my air nozzle in there and blasted it out and have had no problems since.
Re: the paint, I chemically stripped the cases (I wouldn't let anyone near my engine cases with a bead blaster, too many oilways for glass neads to hide in) and "etch" primed them, the etch primer provides a "key" for the paint (VHT engine enamel) to stick to alloy, otherwise it will just flake off with time.
The trouble is that I'd added some "Liquid Engineering Fuel Set" to the fuel tank to remove some water, and I believe that's what did the damage I had a look again last night and with the airbox back in place it's not that noticeable, but when I do strip it down again, I'll get my cases powdercoated. Cheers, Terry.