As you state, the Wescott is an expensive body, but they have a great reputation. Before you go with Gibbon I would suggest you do a search on their name in this forum to learn from the past experiences of others. In particular you might look at the threads started by HenryRifle (Jack) who has built a very nice '33.
You might look at the packages from N&N Fiberglass Reproductions or Redneck Street Rods (more expensive, but well built) as good value offerings. After much research I bought my '33 roller from Duane at N&N, and I have not been sorry. I believe that he gives the best value product on the market today, but you will have to handle things like cowl vent and opening windshield yourself, I believe.