That's a lot of work! I would have given up and started searching for a replacement. In fact, I have a stepside tailgate hanging on my fence as a piece of yard art because I thought it was too far gone to go on the truck.
That being said, your tailgate being a GMC with the letters in the middle would likely be hard to find. My truck is actually titled as a GMC, but I went back with all Chevy stuff because I already had a Chevy grill, steering wheel etc. and I couldn't find the GMC parts.