Yeah, there's no need to take the pegs out of the gloves. I did with the boots though. Also, I widened the holes in the arms so that the glove pegs fit in much better.
My KP body arrived today from BlackOps Toys. Got it for $42 during a secret Cyber Monday sale and had it shipped a mere couple hours after placing my order. They've oddly jacked the price to $56 now that Monkey Depot has sold out of them. I guess those are the breaks!
As has been mentioned here before, the body is a perfect height for Vader. The neck wrap is a tight fit and the Vader head needed a little heat to fit onto the KP neck peg, but you actually get better articulation for Vader to gaze downward at his regular-sized 1/6 minions.
While I was surprised how well most of Sideshow's parts look and fit on the Kaustic body, IMHO it really is essential to pull the pegs from Vader's gloves and boots to have the whole figure hold itself together. The glove pegs are too long to fit securely onto the Kaustic wrist joints, causing the hands to easily fall off. And since I don't have a pair of needle nose pliers, I'm gonna have to make a run to the store before my Vader can be completed.
I should also add that while I admit there is a little loss in articulation at the shoulders, it's partially due to the width of the chest plate getting in between the upper arms coming together for those two-handed lightsaber poses. Also, the arms may have looked a little on the short side in Wor-Gar's photos due to the removal of the wrist ball joint. Putting them back in and using them to connect to Vader's gloves should solve the issue (the KP shoulder joint also has a strange tendency to pull the arms up a little in at a neutral position; the arms are actually capable of hanging down to those Prowse-like proportions). Finally, in order to avoid bunching up the sleeves, I took the drastic step of trimming a 1/4" off the cuff. There's no going back for me now!
Sorry if my observations went a little overboard, but I hope these tips will help out the next guy to attempt this body swap. Even without the secured wrist and ankle joints, Vader is vastly improved on this body. I'll get photos up as soon as he's all finished.