I'm not to sure of your ABC theory, never heard of it before, and Gibson Les Pauls, and Epi Les Pauls are quite different in apperance.
Anyways, if you don't like the SG, i'd sell that, get a valve head, something like a Marshall DSL and 1960 4 x 12, that'd improve your tone much more than changing the pickups now through your current set up. Although changing pickups is a good idea