Yeah I think this was based on something written by Hofmann.
I never tried it myself, but it might work. The question is, how are you going to retrieve the psilo from the methanol? Some kind of evap under vacuum/inert atmosphere would be ideal to prevent oxidation but not always possible. Maybe combining this tek with methanol freeze precip could be interesting to experiment with.
Please do note that both chloroform and methanol are quite toxic, so be sure to use a flow hood or otherwise excellent ventilation/mask , and make sure the product has no remains of those chemicals by completely drying them.
Regarding the nausea, even pure psilo could induce nausea, just like pure dmt and harmalas can produce nausea. Maybe 5-HT3 antagonism with ginger could help, might want to experiment with that. But even then you might still have nausea, who knows, or not have nausea even eating whole mushrooms... I'd also argue that you dont have to worry too much either way since nausea is a part of the experience that might be beneficial too, by putting you through a reminder of your mortality, an extra challenge to overcome and be able to really appreciate being alive. But by all means experiment and find what works best for you.