So I've been reading my ass off and found a way to change isomers thru acylation with hcl (aqueous)! Place your ephedrine hcl or pse hcl into a Pyrex or corningware dish w concentrated hcl (muriatic works!), at least two times volume of hcl to e or pse. Boil. That's it! This isn't exactly scientific, at least not insofar as its not measured nor absolutely perfect, but atleast 25% will change over to pse from e. Simply boil the acid down to half its volume, then start evaporation at cooler temps to avoid evaporating your substrate. The process is reversible with same process. This is called acylation, or basically cooking w acids.