I would not advise to take this combination. Ibogaine has dangerous and potentially unsafe interactions with SSRI's/SNRI's, and I believe that 25i is an agonist of the 5-HT2a serotonin receptor. Ibogaine is known to have dangerous interactions with many different drugs on its own, and it is not a substance I would risk experimenting with in combination with other drugs at all. I have had luck eliminating some of the anxiety associated with certain trips by adding phenibut to the mix, which seems fine. I imagine that cannabis will potentiate the effects of the 25i as it does with psychedelics in general, but I do not think it is a particularly "dangerous" drug to add into the mix. This link to the BL thread of dangerous and potentially dangerous drug combinations indeed verifies that Ibogaine is listed as a "known dangerous combination" for virtually every class of drug.
http://www.bluelight.org/vb/threads/648356-List-of-Dangerous-amp-Potentially-Unsafe-Combinations
Ibogaine itself has a relatively short halflife, but its metabolite noribogaine has a half life of 28-49 hours - but the study I found that has that information was referring to the use of noribogaine directly. Even with that being said, I would highly advise against this combination. Be safe.