RE: GP Super Stearman
The engine is installed in my Taylorcraft (the one in my avatar).
Unfortunately, I couldn't find a photo that shows the actual linkage but if you look at the photo, you can see the threaded hole straight above the carby. If you get a bellcrank (90deg) and bolt the pivot point to this hole, then you get a straight run from the horizontal arm down to the throttle lever with a short music wire. From memory - the length including the clevises was around 2.5 inches.
Does this make sense to you?
Since this is a Stearman thread, feel free to e-mail me offline and I'm happy to elaborate a bit on it.
Regards
Ari