Hi, Guys.
I picked up a brand new/old model Fox 29 at my local hobby shop around twenty years ago.
A 1955 model as I recall.
I broke it in on Powermaster 10/22 50-50 castor synthetic.
The only mod I made was to install a K&B needle valve assembly.
Installed in a Barnstormer, and with a 10-6 Top Flite wooden prop I flew it in Old Time Stunt for around five years and also loaned it to quite a few people to compete with.
All told, well over 700 flights, always with the same fuel.
The Barnstormer is long gone but I still have the Fox and it runs as well as when it was new, with excellent compression and a tight front bushing.
Never ran it 2-4 style - always screaming lean.
Early in the plane's history, I did try a muffler, a well opened tongue type, and the engine overheated.
After that, it was always run with open exhaust.
Never tached it so I cannot comment on engine speed.
FWIW, Bob Z.