Last Saturday evening, I went ahead and took the plunge. I modified my TSR class set up to include more martial arts action. Using Flying Swordsmen as a bit of a guide (plus some stuff I had done in TSR-East, and maybe a little bit of Chanbara that hadn't made it in yet), I came up with martial arts subclasses for the Cleric, Fighter, and Magic-User. The Thief already had one.
Because of that, I got rid of the Monk as its own class. And the traditional "monk" abilities got divided up between the various subclasses. There isn't a direct analog to the typical Monk class now, but there are options to better emulate wuxia in the rules. To replace the Monk, I made a more standard Cleric/Thief hybrid which got the Darkstalker name I had previously as a subclass of Cleric. It's the Van Helsing/Simon Belmont/Vampire Hunter D class.
For the Cleric, the subclass gets the Monk name. In addition to unarmed fighting and unarmored defense (using Dex score+BAB), the Monk gets resistance to ESP, charm, poison, disease, and so on as they gain levels. The Monk gets full clerical casting, but don't get to turn undead and don't get bonus spells for high Wisdom scores (something I'd imported from AD&D). They also use the Shaman spell list (AKA TSR-East spells, drawn from OA, FSRPG and Chanbara) instead of the normal Clerical list.
For the Fighter, the Martial Artist subclass focuses on combat, obviously. They get better unarmed damage than the other subclasses, and since their BAB goes up faster, will have better unarmored AC. They get healing (basically like Paladin lay on hands), and as they gain levels their unarmed strikes can damage creatures as if they were magical.
The Magic-User's subclass draws on Flying Swordsmen and my old TSR-East Xia class (which was modeled on the BECMI Elf class). And it's still called the Xia. Of course they get unarmed damage and unarmored defense. The Xia has a lower Dex requirement than the other classes (11 compared to the 13 the others need), so while they get unarmored defense like the others, the possibly lower Dex and very slow BAB increases will mean they're not as well protected as the others. They gain the ability to reduce damage to the minimum value once per day per two levels. They get MU spells from the Geomancer list (again from TSR-East and its predecessors), but don't get 6th level spells. Instead, they get the Death Touch ability (for Fist of the North Star/Kill Bill fun!). Of course, the target of Death Touch can't have more than double the Xia's hit points or 15HD. And Xia use the standard d4 for HP. So I don't think it will be overpowered. One thing I may change is having it take the place of those 6th level spells, so they could use it once per day at 11th level, twice a day from 12th to 14th level, and three times a day at 15th level. Right now the rules just say once per day but I may modify this in the future.
Oh, and if you're wondering, the Thief's Acrobat subclass has always had the unarmed damage and unarmored defense. Instead of Pick Pockets, they use those chances for Tumbling and leaping. Instead of Find/Remove Traps, they get Escape Artist at the same chances. They can also use Climb Sheer Surfaces as intended and for feats of balance. At higher level, they get to damage creatures with unarmed strikes as if magical, and at 10th level can make supernatural leaps. They don't get to read languages or cast spells from scrolls like a standard Thief, though.
Also for the Cleric, since the Darkstalker subclass was removed, I reinserted an idea I'd toyed with of a Necromancer subclass. They get the "control undead" feature instead of turn undead feature that the Master Set described for undead clerics. Otherwise they're just like normal. And yes, you can still be a normal Cleric and Chaotic.
Also for the Fighter, I renamed the Knight subclass into the Cavalier subclass. No need to have a Knight and a Kensei (two Ks) when there's an established name in D&D lore already (and my previous TSR rules used Cavalier for the "paladin" class anyway).
Finally, to balance out the Thief, which already had the Acrobat subclass, I reinserted the Yakuza from TSR-East. They're a standard Thief in most respects, but get magical tattoos at certain levels. They don't get to read languages or cast from scrolls, though. The tattoos give things like bonuses to Thief Skills or saving throws, resistance to energy damage, and a few other special abilities.
So now the class structure of TSR (2021 revision) looks like this:
Basic Classes [Subclasses]
Cleric [Druid (Yamabushi), Monk, Necromancer, Shaman]
Fighter [Cavalier (Samurai), Kensei, Martial Artist, Ranger]
Magic-User [Geomancer (Wu Jen), Illusionist, Wild Mage, Xia]
Thief [Acrobat, Ninja, Outlaw, Yakuza]
Assassin (Fighter/Thief hybrid)
Bard (Cleric/MU hybrid)
Darkstalker (Cleric/Thief hybrid)
Lark (Fighter/MU hybrid)
Paladin (Cleric/Fighter hybrid)
Warlock (MU/Thief hybrid)
I did almost all of that on Saturday. On Sunday and Monday I did a bit of tinkering and editing. Part of that included switching around which races can be which classes, and the max levels they can attain. That may be something for another post, however.