What would I do? Well, I'd want to play it "by the book" as much as possible. As discussed in the previous post, I've had more than my fair share of house ruling odysseys. So one of the big points of playing AD&D 1st edition would be to experience it how it was / is, rather than how I think it could or should be.
I'll see when I receive the AD&D rule books I ordered recently, and have the chance to read through them again, but in all honesty I think I'd be tempted to run Labyrinth Lord with the Advanced Edition Companion. From what I've seen, LL appears to capture the essence of the early A/D&D rules, while presenting them in an improved and streamlined format. Plus of course it's compatible with all the really great things like the AD&D Monster Manuals and the 2nd edition Wizard's Spell Compendium (which I have a full set of, and am very very keen on).
But is there anything, even at this stage, I can say I would do differently? Any areas where I wouldn't play by the book? Well...
1st level wizards. I've always had a problem with them and their measly one spell per day. So I'd think seriously about giving them three spells per day at 1st level (basically two bonus 1st level spells). Even one extra spell per day would make a big difference. And I don't think a bonus 1st level spell or two would make any difference once a wizard is past 5th level or so.
Specialist wizards. I really like the 1e split between Magic-user and Illusionist - the way they're actually separate spell lists. I also really like the concept of the 2e schools of magic. But I'm not so keen on the watering down of specialists in 2e, by the fact that a generalist wizard (Mage) can cast any spell from any school - which kind of makes the specialists less interesting. So, blessed as I am with the Wizard's Spell Compendium, I would think about only allowing specialist wizards. Yep, no Magic-user / Mage. Just Illusionists, Necromancers, Invokers, Abjurers, etc. And yes that really would be possible. Get this: 231 Abjuration spells, 136 Divination spells, 280 Necromancy spells... So these specialists would have a seriously wide repertoire of spells available, even if they were strictly limited to a single school! Even relatively obscure schools like the elemental schools or the school of shadow would have enough spells to make it perfectly feasible for a player character to specialise in them. I reckon that'd be pretty interesting, and would make for a lot of variety in PC wizards.
Weapon proficiency. While I wouldn't want to go for a full import of the 2e weapon proficiency system, I think I'd probably relax the class-based weapon restrictions a bit. Only a bit. I'd probably say that characters can use weapons not on their class list, but at a (fairly harsh) penalty to hit. Simple.
One thing I really wonder about in old-school A/D&D is combat tactics. To be honest I don't think the combats we played as kids / teenagers were very tactical or interesting. Just your basic hack 'n' slash d20 rolling, as far as I recall. Since playing Savage Worlds my mind has been opened to the huge possibilities of a combat system which provides simple flexible rules for characters to perform all sorts of different (i.e. not just "I hit it again") actions in combat, and for them to make a big difference as well. In Savage Worlds a huge range of potential actions can be imagined, described and resolved with a couple of really simple mechanics - everything from intimidating or taunting opponents, to throwing sand in someone's eyes, to trying to tangle them up in a rope, to putting them off guard by briefly pretending to surrender. The big revelation here is that "non-combat" characters (like, for example, 1st level wizards who've fired off their daily magic missile) still have something very valid, useful and interesting to add to a fight.
I don't have much of an idea how I'd handle stuff like that in AD&D.