Realigning the Thrust Washers is My only fear, doing it this way.
I grease the T-washers to the case, and because I assemble it with the face of the box down, they stay in place.
My Left hand doesn't work so well after a Tendon Transfer Surgery...
Oh boy, that'd tough,
Is there enough room to work in there after the Gearset is in, to move the Cluster around?
Yes and no. Yur gonna have to stand her on her nose so you slide the cluster into position and have her stay there. But to do that, from being slid together horizontally, the tail will have to be bolted on upside down with the cluster pin-hole exposed.