I have spent a good chunk of the last 24 hours contemplating how one would convert Paizo's Pathfinder: Rise of the Runelords to B/X.
The largest obstacle to overcome with using B/X for a published campaign such as this would be the XP pacing. But I think this could easily be overcome with re-calibrating the treasure. One of the nice things about B/X is that lots of treasure doesn't really unbalance game play.
I have never played such a campaign. I typically use published adventure modules for the larger sites in my sandboxes but running an adventure path would be quite different. So different from my regular style that I am not too sure I could pull it off. But for some masochistic reason I kinda want to try it.