I would definitely be careful taking MAO-A inhibitors with a new-fangled substituted tryptamine. I believe 4-HO-MET has some reports of being used with smoked rue, but I don't think I heard anything about full-dose MAO-inhibiting harmalas. I would be cautious still even smoking rue with the MET as I know for myself the thought that this could go awry is enough to turn my emotions towards the shakier.
MAO-B inhibitors are less of a problem for psychedelics in general as I understand, since that enzyme system is supposed to focus more on the degradation of dopamine/other bodily phenethylamines, and the main thing we're trying to avoid with the MAO-A inhibitors is serotonin syndrome due to buildup in the synaptic clefts.
If you have good information that Reynoutria (=Fallopia/Polygonum) multiflora is purely a MAO-B inhibitor, or a weak one at that, I don't think you'd have problems combining with very small, tentative doses of 4-HO-MET to test if any problems arise.
Personally I have some 4-AcO-MET and I really don't care for it. I find it's has a similar electricity in my nerves as mushrooms, but does not provide much of any of the deep thoughts, universal connection, insight, just a bunch of 'ok' visuals that seem much more human-oriented than the 'otherness' of mushrooms. Also you don't have to worry about taking MAOIs on psilocybin. It's more potent but I haven't heard of anyone dying. Terence McKenna and other have said that it's not a good time on large doses, but afterwards no damage done it seems.
When it comes to mixing with these new chems, you're kind of on your own, so do be careful.