I really hesitate to jump in here since I had a lot of confusion over trans shims myself. It's very confusing and the information out there seems to be very limited. So some of the things I did required my best guess and I won't really know how well I did until sometime next spring when I hopefully will take the first ride. But for what it's worth, here's what I THINK is right.....

I didn't put any shim after the snap ring. I can go through all gears on the bench, can turn shafts in any gear and can't feel anything rubbing. If anything the shafts have too much end clearance. Definitely not too little.

As for the bearing on the other end I'll post a pic of what was in mine before tearing it down. Looks pretty much like yours but I do see an x on the inner race which I can't make out on yours. But you said all was good before so who knows?
The other end of that shaft has the half moon keepers and the thin washer that keeps them together. During assembly they are prone to falling out/ apart. You have to be very watchful that they stay together. If that happened, even partially, it could possibly cause a rubbing problem on the other end. I put a little dab of wheel bearing grease on mine to hold things together during assembly.

It seems like if the snap ring you're talking about rubbed against anything it would be the inner race of the bearing it butt's up against which shouldn't cause any problems that I can think of..

So probably didn't help you much with all my sketchy info but at least you know other's have gone through the same thing. Wish I could be of more help.

It doesn't. I think I said that already.

Glad you jumped it, I agree about sketchy info, I think it’s made worse the way they mix with 250s.

Goes 1 -5 smoothly on bench. I am going to fit things up and if end play is in spec go with it. No hurry as jug at machine shop with 120€ piston

My bad, I missed that
now I got my answer, thank you!

MarkT - you were correct turns out the sprocket side when snuggled up controls clearance between 1st gear and case

Glad to have unconfused myself
Thanks !