There are so many ways to skin a cat.
Existing cork can be sanded to new profiles, there are tons of videos on that and replacing cork. Sort of 101 rod building.
Modifying grips with shrink and underlayment like how i demo on this net is another option. Rod building shrink like xflock or you can get eletrical grade shrink. Either work great for improving grip. If you are sealing cork with anytging over it make sure it is 100% sealed and water tight, because if water gets in it cant get out easily and can rot you cork an potentially ruin the blank. trailLite Desings - ti net mods