It wasn't difficult at all. I brought a sauce pan of water to boil, and dipped the reel seat in for a few minutes. This loosened the epoxy/hot glue adhesive, and a pair of pliers allowed the hardware to slide off easily. The cork was cut of with a utility knife, and then the blank was cleaned up with 80-100 grit (I don't remember exactly, but that's close enough) sand paper. Because blanks get thicker toward the butt end, it's standard to ream the inside of the cork to match that taper, and slide it onto the blank from the tip end. This was a two piece rod, and I had little interest in removing the guides. A check check showed that the blank diameter was 1/8" greater at the butt end of the grip, and I reamed the cork so that it could be slid from the butt up to the winding check. A few wraps of masking 1/4" below the winding check kept the grip centered. As a builder of precision R/C airplanes, adding weight with excessive epoxy goes against accepted procedure, but I removed so much extra weight by getting rid of the over-sized grip that I was able to sleep that night.
The extra amount of epoxy needed wasn't all that great, and the 1/8" I mentioned was the difference at the ends of the grip. The average change in diameter was much less than that, and maybe 1 teaspoon of extra epoxy was required to fill the void. Adding a couple more rows of masking tape would have reduced that, but it wasn't really an issue. The original cork did not have an insert for the reel seat hood, so the new grip and reel seat were quite an improvement.