I'm about to return another momo adapter hub that's supposed to fit an early (1970) since it won't go down far enough on the shaft to engage the directional canceling. It's a shoulder on the steering shaft that keeps it from going down far enough. I noticed in the parts diagram that this isn't a "shoulder" but a "bushing". If there's splines under this bushing, I think the adapter would fit.
Before I pull the wheel yet another time, can someone tell me if that there's spline under that bushing?

When replacing a std wheel with a Momo wheel & hub you don't need to remove anything apart from the original wheel (& transfer the turnsignal cancelling ring over to the new hub).