Homebrew '82: Training for next level

I hope to get back to making more posts outlining my evolving retro-game, Homebrew '82. As I may have said before, it's not intended to pave any new roads into uncharted, gonzo territory, just to serve as a "re-starting point" for a game that I'd feel comfortable running. If I do ever decide to start DMing again, it would most likely be with friends who've never played, or maybe just tried it in the 1980s, so system won't likely be their big concern.

Anyway, I'm having fun with thinking about what happens when PCs need to train for their next experience level.  This can be an interesting "mini-game" (sort of like character generation) in itself. So instead of just rolling for new hit points and making some changes to the character sheet, what should happen?  Well...

1. The PC in question needs to find a mentor or master who holds an experience level of at least the one being trained for.  (There can be some interesting role-playing when the student surpasses the teacher, and thus needs to go in search of a new master!)  Some mentors may charge for their services, and some may not.
2. The PC rolls 1d4 and adds the result to his or her current experience level.  That's the nominal number of weeks that the training will take.  If they break it off before the time is up (e.g., Luke leaving Dagobah), it's got to start all over again.
3. There's a chance that the PC's prime ability score will increase by one.  (This score is typically the standard one; STR for fighter, INT for magic-user, and so on.  But it may be different. A more street-wise or "minstrely" rogue might have CHA rather than DEX. A "meatshield" fighter may have CON rather than STR.) An existing score of 3-9 needs a 6 on 1d6 to increase.  10-15 needs an 8 on 1d8.  16 needs 12 on 1d12.  17 needs 20 on 1d20.  If it's 18, regular training can't increase it further.
4. For fighters and rogues, the training involves lots of physical exertion -- and thus lots of probable damage and healing. There's a chance they will end the training having only a fraction of their new HP total.
5. For magic-users, there's a chance of either physical damage or insanity from spell-casting mishaps!
6. For clerics, there's a chance of a mystical dream or vision from the PC's deity. Depending on whether they're in the deity's good or bad favor (GM decides), they would be granted a permanent good or bad modifier to their daily miracle-casting points.
7. The GM will also roll on an "event" chart that give some flavor for how things are going with the training.  Personality clash between the PC and the mentor?  Another student jealous of the PC?  Maybe an enemy of the mentor spies on the proceedings and now considers the PC to be an enemy, too!
8. Finally, if the full training ends successfully, the PC rolls for the new level's hit points, and computes all other new-level quantities.

This doesn't look like it would take much time for each character that's gaining a new level, and it adds some good role-playing flavor to the process.