Ok, so I figured out it: because I "wuz doin' it wrong".
I thought the bushings simply pushed in from the outside; nope, that would be too easy, huh? Instead, you have to press out the center pin of the shaft, and drive the bushings from the inside outward. That's why there's a semi-circle flange there, so they'd fit and not slide all the way out...
Those That Know are thinking "oh, he didn't know that?" Nope. Remember, my bushings were all completely gone, nothing left in there.
So I managed to correct that situation in a half-hour or so with a bench vice, c-clamp, and judicious use of varying sockets and washers. Mystery solved.
Shifts good now, too.
- GA