turnip_farmer
Adventurer
Sounds like it is working well and you are having a good time with it so great.
I would expect some issues with the system that 3e-PF-4e-5e started to address regarding older D&D. Magic-users having one spell. Save or Die. Energy Drain. Healing. Low Level Thief skills. Death at 0 HP.
I have not looked into OSE's specific advanced options but alignment rules for a lot of AD&D classes (paladin, ranger, monk, druid) can be issues.
Just be aware these are common issues with older editions and might come up as they and you get into it.
I've gotten my players to try out DCC RPG to scratch the old school itch. It definitely treats the ease of character death as a feature, and sets out its stall from day one so the players know what to expect. If you play it as recommended on the rulebook, each player behind with multiple 0-level characters, some of which are guaranteed to die in the first session.
It does slack off a bit if any characters survive past the first couple of levels, they do not die immediately upon hitting zero (though some things can still kill in one hit).
Wizards do take a bit of time to get off the ground in this system, but that's the trade-off you choose for cosmic power at higher levels, and it usually only takes a few weeks of in game time to get a few spells. The slow pace of healing requires spending days sitting around recuperating in a village between adventures, so that 'few weeks' doesn't need to take too long if the GM is not vindictive.
Thieves get some pretty good skills right at level one.