I think you should revisit the prop issue again, even though you don't think that Bob is correct. The manual has a range of 12 X 7 to 13 X 7. The 13 X 6 should work, but maybe try a 12 X 7 or 12 X 8 to get an idea of a good needle setting during break-in if you are dead set on going with what the manual recommends.
Also, if the engine is not throttling up after you take the glow driver off, I would venture a guess you are already on the rich side so you don't want to richen it more.

You can try taking the glow driver off and then advance the throttle slowly. Once it gets to a point where it won't get any faster, lean the needle just a little bit. Keep doing this until you can get a good RPM out of it at full throttle, but be careful not to run it too lean. It will take some time, but you should be able to get a good feel for what it is doing.

T.