Somebody has to be the first person to do that experiment. If it hasn't already been done, then it might as well be you if you're interested, and it's not a waste as long as you learn something from it. Cocoa may contain an MAOI, but I'd be suspicious of how much actual cocoa is contained in commercial chocolates. My understanding is that MAOIs usually have their own perceptual effects, so if you don't get that from eating a lot of the chocolate by itself, perhaps that indicates that the MAOI content is too low.
Anyways, it will be cool if it works.