One danger in rebuilding a classic car is falling into the trap of what some call "Washington's Ax" syndrome. If you're not familiar with the story, it's a bit of a shaggy-dog narrative in which first the handle and then the blade of George Washington's famous ax are replaced, resulting in an ax that was once completely historically accurate, but is now just an ax with all-new parts.
In terms of car restoration, there are certain areas where simply replacing parts and panels can go too far. A warped undercarriage, totaled frame or similar large-body details can seem easy to fix, but when dealing with such large pieces of metal, it's often the case that internal stresses over many decades can destroy the body so fully that what appears to be a show-quality machine is nothing more than a thin memory of the car's original state.
It's important to stay in touch with your original plans for undertaking this project: Are you after a street-legal vehicle you can drive? Are you looking for a classic show or collection piece that doesn't move? These decisions are essential at the outset and should remain at the forefront of any financial decisions that you make.