It is quite easy to rework the system, really. Just toss it all in the garbage and fetch the 2nd edition books.
I love AD&D 2nd Edition but it does have issues of its own, mainly melee classes being fucking boring and a joke. Fighters in the PHB get fuck all. HP, lower Thac0, proficiencies and specializations.... and that's it? The Combat & Tactics splatbook intodroduced weapon masteries.
The problem with procifiency, specialization and mastery is that it doesn't really open up new options for the fighter. It's just straight up better hit, more attacks and maybe a tiny damage bonus. It's dreadfully boring.
The class kits from the Complete Fighter splatbook didn't really add anything of relevance either and most of the kits were purely RP fluff anyway. IIRC, only the Berserker kit even did something new in terms of class mechanics.