Great work Mark , Danny sent me a couple of youtube clips about 'balance beads', used in tyres , to understand how it all works . Amazingly simple once one understands the process.
I don't think it can ever be perfect though, because of the ' hunting ' gearset used in the gearbox . That means any imbalance in the engine will be in a different place at the prop shaft every engine revolution .
I suppose an extra Balancemaster mounted to the engine flywheel may take care of that .
cheers
Jim G