As promised, here is the Vivell 35 running. It tachs 9470 with a Rev Up 11-4 wood. It does 9150 on a B-Y&O 10-6.
Fuel is Coleman lantern fuel with 25% Castrol SAE70 m/c oil
In terms of "propwash", it seems to have lots more thrust with the 11" prop
That's not bad performance for a '40s engine. It probably would do a bit better on glo, but I didn't try glo.
Floyd