On the all parts won't fit.
The a3 support bearing is the only bear in the room.if you find an a35 transcase that fits your case you can run an a35 crank in an a3 using a a35 Clutchbell hubs shoes gearset are slanted but can be swapped for straight cut a35s.
Pros use off the shelf puch and Tomos cylinders and pistons. Con no great a3 shoeyness nor the added value of the a3 hubs & sturdy clutchbells