hpg, once you get the finger grooves off there isn't a lot of thickness left to work with. Grinding to make new finger grooves won't work. If you want new finger grooves you can build the grip up with accraglass from Brownells or something similar.
The easy and fast method is to stipple it with a soldering iron, it makes and extremely good gripping surface and is extremely durable. If you are patient and carefull it can also be really nice looking.
The downside is you might have a harder time selling the gun if you ever wanted to sell it, but having it work right for me is more important than resale value especially with something as utilitarian as a Glock.