The powertron and powertron+ pickups are killer.
They make them in normal humbucker size, but as with everything else, geometry matters.
You can buy pickup rings from TV Jones that fit a standard humbucker ring screw pattern, but have a smaller opening to fit the standard filtertron geometry.
If you are going to put filtertrons in your Gibson, I recommend that you get the standard filtertron pickups, and get the correct rings to mount them.
The humbucker size ones are really good, but if you instal the narrower classic type, its the last 10%.
Whichever way you go, highly recommended