Sorry not to have replied sooner. Here is our GF. As you'll see, even with the motor out, it is a different model from yours. The clearest difference that shows even in very shadowy photos is that yours, and most others have the drive belt running fore and aft beside the off side wheel.
Ours has the gearbox under the seat with a 90 degree take off to the belt which runs across the chassis, under the drivers legs.
At the moment I am refurbishing the belt drive tensioning pivots, rods & levers. Understanduing how it all operates is difficult as the "TypeA" parts diagram is no help at all.
If anybody has a GF of the type in this photo, a photo of the drive belt tensioning system assembled, would be a huge help.
General progress: The Petter AVA1 is out. Cylinder head and fuel injection pump system is fully overhauled. Piston & cylinder look ready to go.
Down below, I have shoveled an inch of sludge from the floor of the crankcase and found the oil pump, the early plunger type. The big end journal is scored which may be a problem as the flywheel will not come off the crank and so tha crank cannot come out for a regrind. But we have a cunning plan to manually dress the big end journal with the crank in situ. The guy who came up with this idea is very capable and would not suggest it if he didn't think there was a sporting chance of success.