Injury,
Any ball drilling on it's own is basically no different from left handed to right handed. By that I mean that there is no difference in how you would drill a ball as far as depth of holes is concerned (lefty vs righty).
Drilling into the interior part of the ball is an interesting comment. Normally, with a finger tip grip, the finger holes are drilled approximately 1 1/2" deep. The thumb hole would normally be approximately 2" deep, up to 2 1/2" for thumb slugs. These values should not change regardless of hand preference.
Edited on 3/23/2007 8:19 PM
Edited on 3/23/2007 8:19 PM