Seymour Duncan Trembucker pickups with metal covers own't fit in the stock mounting rings. They come with their own matte black flat mounting ring, which is of course useless with a Les Paul anyway. Trembuckers without covers will fit the stock mounting rings but they still look a bit odd up close, clearly scraping against the sides of the mounting ring in some places and leaving large gaps in other places. DiMarzio F-spaced pickups are the same dimensions as regular humbuckers and their pole pieces align with Epiphone bridges perfectly. Of course, DiMarzio do rather suck if you want a more vintage style pickup though. In that instance I'd recommend settling for regular SD humbuckers (or go boutique, though that costs a lot more). The pole pieces will be slightly too narrow for the two E strings to align properly but this isn't too much of a problem - I find simply raising the pickup a couple of mm more than usual sorts any response problems that can come from misaligned pole pieces. Pole piece alignment matters more with single coils than humbuckers anyway.