I don't know if I'd personally be killing such a rare and gorgeous plant like a lophophora williamsii just for an extraction.
They take over a decade to reach maturity. A pedro, peruvianus, bridgesii etc will grow a foot a year on each limb and would be far more than enough for an extraction and better yielding overall. It would be a lot more sustainable to stick with those varieties. You'd need a fair few mature peyote for a decent extraction or only a foot or two of pedro.
Peyote have other actives in it as well, an extraction is unlikely to extract them all. I'd recommend sticking with ya classic trichocereus cacti listed above.
Disclaimer: All my posts are of total fiction.