Billy, HI!
NB: Ian, I think both the Ringmaster and the Gyrator were in Model Airplane News...
Billy: I built Williamson's Ringmaster about 20 years ago. The main differences were that the Gyrator has flaps and that odd bellcrank/leadout layout. Both, I believe, are OTS eligible, so the Ringmaster is the better choice, for the no-flaps bonus, edit to add: for the more reasonable leadout position, at least. (edited because I'd mistakenly recalled the Gyr as having flaps...)
Harry W also did an article a short time later, probably also in Model Airplane News, about vertical CG. He should know. Both the Ringmaster and the Gyrator build with the vertical CG WAY too high. Both planes fly banked right because they are topheavy. My Ringmaster eventually died because of the difference in tank height from inside/upright to outside/inverted. I had used a moderate power .19 instead of the indicated howling .29 - perhaps, with the added power, the bank would not have proven fatal. It went too fat, inverted, to get back upright - I let it fade into the ground, mostly because I was tired of fighting that built-in flaw... If I'd inverted the engine, it might have improved things, but it wouldn't have been Harry's Ringmaster...
An inverted engine would also have made the tank installation less fussy - there is D*** little room above the mounts to hold fuel for an upright engine in both of these. The fuel tank bay, if the engine were inverted, would be better.
Yeah, the airfoil is thin by our current standards, but Lift calculates from the square of velocity. With a honking .29 of that era, or a decent LA25 today, either one could fly fast enough to have plenty of potential. BUT, that vertical CG thing will still be there...
As much comment has put forward, bellcrank location is essentially irrelevant. What IS relevant is the leadout location! On the Gyrator, that is much too far aft. Back in those days, we didn't trust centrifugal force to keep the lines tight enough to assure control. Look at other plans from the era: huge rudder offsets, generous engine offset, aft leadouts.... Today, we know better. And, we know more about vertical CG...