There is a club for these engines but I don't know the name of it. I met an older gentleman and his wife this past spring at the local RC swap meet and he had a nice collection of the little OB's for sale so there may be someone reproducing parts for them or has original stuff.
The older outboards used straight shafts off the motors to a bevel-geared lower unit.

I found this: http://toyoutboardmotors.com/scott-atwater.htm