Thank you so much for documenting this project, so incredibly interesting.
The plastic fuel filler flap and dinky spring is so fragile many folks have broken them off. Myself included. Much care is needed when filling the tank not to hit the spring side of the flap with the fuel nozzle. You'll know when the flap fails, engine check light leading to emissions fault code. Have you created a better mouse...er fuel trap door?
That is a very impressive undertaking and project. Do a search on the forum.
Someone else has done the same thing. The only other person I know that could undertake this would be specracer!
he may even have enough parts to build a car at this point