Also while i'm here I've seen posts about not following the clutch assembly drawing diagrams and when putting the steel discs/fiber discs in you start with the fiber and not the steel like the drawings?

"When installing the discs are you going by the parts diagram?

Don't. Stack needs to start with a friction and end with a steel."

Gear indexing not properly adjusted will certainly cause the problems you have been having.

Clutch trust washer missing isn't a great idea, and hopefully a new one, along with the indexing adjustment, will cure your problems completely.

The washer that is part of the bearing isn't drawn in the pic if that's the one it sounds like you mean & can only be bought as the flat bearing complete.
Hope it works out although not related to the jumping out of gear problem.
Just my opinion--but--Once it's in gear & settled with the roller arm holding it in between the pins the change arms job is done, so if it jumps out after that then, i think dogs & slots rounded.
But if it jumps back out under acceleration while power shifting during the change process then it's possible the arm's not pulling it far enough in & dogs are kicking it back before fully in.
Anyway, who the hell does power shifting on one of these old girls--umm, [me, dare i say, & standing in the corner].

Ok got it all put together and so far so good, not sure if i'm just shifting better or what I did helped any lol

Rundown of work:
On the other side of the shift shaft it had a circlip and washer but it wasn't the stock and there was a lot of in/out play on the shaft so I replaced that and it doesn't move in/out now.
Replaced that clutch thrust washer.
Then I did the adjustment on the gear indexing as well as a new spring on the shift shaft because it was cheap

Congratulations!