Having successfully done a '56 'Bird previously, you know better what's ahead than most likely do.
My understanding is that while '55 and '56 'Birds appear very similar, there are many differences in the 'bones' of the two. The change in the thickness of the steel used in the frame sections from the first year to the second would be an example.
Several acquaintances here in the Northeast have emphasized the wisdom in obtaining as complete, correct, and 'solid' a car as possible. Their point has been that while more expensive to obtain, you'll expend far less time, money, and effort in accomplishing the restoration.
There are a number of 'Bird owners who are Forum members. Perhaps they'll be able to be of particular help as you work through your undertaking. Actually, anything that's y-block or y-block vehicle related, there are an amazing number of knowledgeable and helpful owners that are quick to share their hands-on experiences.
Best Wishes with your project, Coyote.
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York