If he looks like a straightasanarrow old guy, who doesn't know about pscychedelics and doesn't wanna know, you might wanna put your librarian costume on, and ask for them by the botanical names.
It's probably best to ask for San Pedro and Peyote by their botanical names, no matter who you are dealing with, as a cacti grower should know this. I called a couple of nurseries the other week and the response when you ask for something in its botanical name is very different (If they aren't some stupid teenager). Also I spoke to a cactus specific nursery during summer and they didn't really want to talk to me after I said San Pedro. I'd expect they'd get a lot of idiots calling.
Trichocereus pachanoi --- San Pedro
Trichocereus peruvianus --- Peruvian Torch
Trichocereus terscheckii --- Cardon Grande
Lophophora Williamsii --- Peyote