The best builders are the ones that listen to good advice. Even in the very early days that we all are trying to recreate, you'd see cars that evolved slowly over time, most famous customs had early iterations and were updated or changed as time went on. Once you got your floors patched up and your seats put back in, focus on getting the engine running and the car driveable, with brakes and tires and a clean gas tank. Get the lights working. Little/None of that work will go to waste even if you do end up changing the suspension or drivetrain later. Then do some bodywork and/or mild customization. If you make it that far, you know you'll be able to follow through with some of the more challenging projects. And you might be surprised at how well these cars drive and handle on properly set up original brakes/suspension and engines. It's a whole different kind of driving experience.