If you fit castor correction bushes or arms you will make the propshaft worse. The gearbox UJ angle gets a tiny bit worse plus the axle UJ straightens out, so you get the pulsing in the driveline that increases wear and makes a racket when you are coasting.
Tomcat Motorsport make a 6 degree (3 or 4 inch lift) castor corrected swivel. You should not drill your existing swivels, they will become too weak.