Derek, I put another full 16oz of Davis Plane Fuel through my .65 conversion today. I used a more suitable prop and took my time to make sure I got it optimum.

OS LA .65 blue
Newer Davis head with annular fins.
Fuel==Davis Plane Fuel for bushing engines
Prop==Bolly 13.5x8
RPM about 50 rpm below peak 9,250
Idle 1750 and slightly burbly

Clean throttling and very smooth.

I took the fuel level right to slurping bubbles and it simply quit when there was no more fuel, imagine that.