When you modified the 3 cylinder Suzuki to run after tilting it 70 degrees without oil surges how did you do it? Is it as simple as modifying the oil pickup? I am giving some thought to modifying one and you have lots of ideas and experience.
Tilting the G10 at 70deg over on the exhaust side is as simple as modding the oil pickup and sump, cutting the inlet manifold and welding on a tube to attach a side draft CV carby, the distributor position is OK for a gearbox (adapted Rotax ‘E’ is best - inc. starter), but it may get in the way of a belt reduction - I’ve seen it relocated to the side of the head and belt driven as in Raven’s setup. Apparently tooth belt reduction without a dampener doesn’t work for the 3 cylinder - creates too much vibration, wouldn’t be too difficult to put a dampener inside the prop pulley as Raven has.
Since the stock motor is only about 55HP, a multi Vee belt or multiple Vee belts could work, and if hand propped would weight the same or less than a Rotax 582 with gearbox and muffler.