I bought a tailgate for my '50 from the Truck Shop in LA. They tend to have cheap (lower quality? probably same parts as everyone else) aftermarket parts but the tailgate I got is very nice. It's identical to my original down to the gauge of sheetmetal and the lettering. Except no dents.

So I'm very happy with it. I think I paid $150 for it. If the part has "chevrolet" stamped on it then I think it has to be approved and liscensed by GM for restoration parts. I think you'll probably be happy with a new tailgate. It's much easier than pounding out the old one. I'm still researching bedsides, though. Good luck!