I can not tell you what to do, but I can reassure you that there's no problem in combining different cactuses. They all (T. pachanoi, peruvinaus, bridgeesi, L. williamsi, etc) contain mescaline in different amounts, so at the correct dose the combination would be almost indistinguishable from a mono cacti trip. Almost, there are some slightly psychoactive alkaloids that differ between the species, but this is not a problem. It's at least not something I've heard of. I would say you can combine them however you like, just focus on the dosage (whereas I always recommend extracting to be certain)!

Have you used mescaline before?