I have not got a clue how many "N" reg GV's there are in Europe, or on 135, but there are many other registrations that will accept the FAA ticket around the world and I have seen quite a few GV's on those. I would guess thats what the poster is interested in, for a European pilot interested in 135 ops, that would probably mean working in the US and I think the work permit would be more of a worry than the licence.