I know I've mentioned it before, but it bears repeating: in my ongoing Dwimmermount campaign, I'm using Labyrinth Lord as the base for my ruleset, but I am modifying it by using bits of both Original Edition Characters and Advanced Edition Companion to bring it closer to the LBB + Supplements flavor of D&D I prefer these days. It works pretty well, all things considered, but, even so, I still find there are things I need to house rule in order to bring it closer to what I want out of the game. That's not a knock against Labyrinth Lord by any means. It's a very good game and I think I can say, without fear of contradiction, that Original Edition Characters is probably the closest we've yet seen among the clones to a "pure" re-statement of the original rules.
I still think it'd be nice, though, if there were a stand-alone volume that (perhaps with a single supplemental volume) gave me OD&D without any contemporary accretions, so far as that's legally possible. To a certain extent, simply taking Labyrinth Lord, swapping in the material from Original Edition Characters and making a few other changes here and there (like ditching certain spells -- know alignment, I'm looking at you) gets you about 80% of the way there, maybe more. But I can't point my players or other interested parties toward a single book or PDF that gives them all the goods. OEC isn't a complete game but rather a supplement to LL and, while I appreciate the reasons for that, I think it'd be very helpful to have a complete-in-one-volume OD&D clone. It'd be really useful too for newcomers interested in the origins of the game, so we can all point them toward this clone and say, "OD&D was like this."
In the course of working on Dwimmermount, I've been slowly producing a document, one that uses Labyrinth Lord as a base and then makes changes to bring it as close to OD&D as I can under the terms of the OGL. When I'm done with it, I'll pretty it up a bit and make it freely available as a text file. Maybe some day I'll even give it a proper layout, some art, and sell the thing, but that's not my immediate plan. I already own the LBBs + Supplements, so there's no need on my end for such a clone, but I don't imagine every gamer out there interested in giving the original game a whirl owns them all. So, I think there's utility in such a project, even if it's limited to a few weirdos like me.