Just an update for those you think their gms .47 fuel supply might be due to their fuel system and not the motor itself:

Installed and ran through 2 tankfulls on the ground of my gms .47 replacement, the magnum .46a, then leaned it out properly, richened it to lose about 300 rpm and went nose up, and the leanout/quit problem was...........gone completely. It was indeed the poor fuel draw of the gms .47 that was causing the problem, not the fuel system.

As a side note also proving the poor fuel draw problem, when you prime the magnum .46 by opening the throttle, covering the carb air inlet with your finger, and slowly turning the prop till you see fuel in the line make it to the carb, the magnum .46 takes about 2 motor revolutions to get fuel to the carb where the gms can take 10 or more, and once you stop turning it over, on the gms you can see the fuel immedietely start flowing back to the tank where on the magnum it stays full with no backflow.
I don't quite get why it backflows, but it does.

Dean in Milwaukee