I've fitted Sportscraft swivels under standard VW height adjustable captains seats without any problem. For the drivers side the best option is to have the handbrake bracket lowered (removed from the seat box and welded back on lower down) and trim the bottom off the plastic cover.
Rotating the seats only requires them to be at a level so that the plastic seat skirt clears the seat box and the handbrake is off (in gear) to rotate the drivers seat.
There are two versions of these swivels, a normal and one with the swivel centre high enough to clear a leisure battery under the seat.
Jennings seats are one of many supplying these swivels