take it to a local architect. Not only will they know the local codes and be able to help you during the build, but they will (or at least should) be more knowledgeable on local materials, recommend suppliers or products as well as builders, help with energy improvements for your area, etc.
I do not know however the legal items and costs associated with having one architect modify another's plans. Our firm has a buy out or sell the cad files to whomever wants them. It does not cost much though, but still another fee involved. Definitely do not leave it to a builder to make design or code changes/decisions. I have worked with too many builders that are clueless. They know how to build according to plans, but most do not know WHY the plans were done they way they were.

Thanks lzerarc. Good advice. Was also wondering from those that had design changes made to the pre-purchased plans if anybody had experience with the original architect. a.k.a. Don Gardner, make the changes from a price point perspective.

DCRanger...i just posted on my original post. But Yeah...I would go to Architect in the area you are going to build, especially since you don't live there currently. We figured it to be about the same darn price once all the modifications were done. It would probably save you a lot of trips back and forth and a lot of headaches down the road. Good luck.