I would like to try this combination. I realy like cactus. But i find that cactus visuals are a bit lacking in colours. Datura increases the colours of mescaline significantly, but i still find that almost all other hallucinogenics, LSD included, give more colourfull visuals.
Since the active stuff in calamus (evening glory thinks it's no alkaloid) probably bears many simmilarities with mescaline, i figure that they may well go toghether, but the only thing is that calamus is also known to cause vomiting if it's not properly prepared.
Since cacti contain MAOI's they might increase the risk of vomiting for many, many hours...