I'm guessing your looking at at a 2e++ edition, which takes a few things from 3e/4e and keeps the rest right?
Players Options are your friends.
My own "perfect" 2e might look like this...
Ability scores: no matter what, dump exception Str. I'd use either Basic/RC's ability progress (9-12 +0, 13-15 +1, 16-17 +2, 18 +3) or 3e/4e's (bonus equals ability score -10, /2) but if you wish to keep the other scores the same, I have an excellent alt Str chart removing % Str
Races: I'd take a few hints from 3e (elven wpn profs, gnome cantrips). Add half-orc from PO/Humanoids HB.
Classes: Fighters would do well from the weapon-mastery rules in PO: Combat & Tactics. Wizards might do from something akin to Reserve Feats from Complete Mage for at-wills (make sure to add the new specialist bennies from Spells & Magic). Clerics and other priests might be served with the cure-swap from 3e. Remove that silly level cap/fighting requirement from druids; high level bennies can be extrapolated from the cleric spell chart, the mystic (Faiths & Avatars) XP chart, and the 3e druid/heirophant abilities. Thieves need a lot of love; I'd look at giving them some of 3e's defensive bennies (uncanny dodge, evasion) and perhaps fixing backstab multiplies for extra +d6 damage (or just fixing backstab to work closer to SA, making more useful).
Skills: The trained + 1/2 level system should work fine.
Combat: I like flipping the AC upwards and replacing THAC0 with BAB. Not sure on saves though. It might be possible to replace these with 3e's Fort/Ref/Will
Spells; Use Spells & Magic update spell lists, ESP its updated cleric spheres.
FINAL THOUGHT: If your big on this type of idea but don't want to put as much leg-room re-writing the PHB, I might suggest looking at Castles & Crusades as a baseline rather than 2e. It did a lot of work for you (upwards AC, re-jiggering classes) and adding a few new powers (at-wills and a skill system) shouldn't be too hard there either.
Anyway, good luck.