You can tap the brass busing and then remove with a puller you make yourself (simple to do). I dont recommend this on one of these gearcases but it could probably be done.
You CANNOT install the clutch dog detent ballbearings on a 1990 3-lug clutch without the installer tool. On the 2-lug clutch dogs (pre 1981-2ish), you can.
Even with the tool, it is very frustrating. My first one took me literally 3 hours. Ive got it down to 10-15 mins now. There’s only 1 way to get it back together and everything is coated down with gearlube if you catch my drift….