Hi Ted,
I am brought back to the article on Juri Sirotkin and his 1964 WC. The prop was ID'ed as about 10" X 4" pitch.
And it was reported his engine was turning pretty fast. Seems he had one of the first high rpm low pitch that was highly successful! 
BIG Bear
RNMM/AMM
Hi Bill
There were many many people that used hi RPM 40 or more years ago in Stunt, Even Noblers with FOX 36X turning up along with Johnson and K&B engines spinning very fast. I had profile stunt planes over 40 years ago that I used FOX 36s turning 4 to 4.5 pitch props, along with ST 35s, and a couple of other engines I ran at Hi RPM. This was NOT uncommon.
Many people back then did try to run the FOX 35 in a very slow deep 4 stroke..kinda like Geiseke did, but the engine almost shutting off in the wingover corner wasn't anything that appealed to me. So when I did use a slower FOX 35 on my Smith Nobler I used the 35 with lots of nitro and a 5 pitch prop.
I got a hint on that by smelling Billy's engine running

, plus there was always lots of Missle Mist hanging around my house
Regards
Randy