As regards the BIA cowboy shirt I don't think it has any relationship with Alchemy by design as in fact, as Jack Sonni writes in his memoirs that MK nicked the shirt off him!
I have always taken Alchemy title and the artwork used on the album portray the intent of a transformation from one thing to another. This can be read on a number of levels from studio band to live performance or perhaps more so, from a basic guitar band to grown up international rock band. Clever.