One big problem will be your "shop rate".
Working on hot rods, muscle cars and race cars is a highly skilled job. People that do it for a living charge a permimim for their services. Now you wanna make a profit off that and that is fine BUT it WILL require your shop rate to be even higher than most other shops.
The problem (as I see it) is this.
Your busness plan is basicaly all mark up.
That is a failed plan. Why would anyone buy your marked up parts?
We have the internet now days.
So parts sales are a wash.
Your labor rate will be higher than competing shops.
Not good.
Add in a classic 60s diner and you could REALY burn cash quick.
This is just my opnion but i do work on old cars for a living and I did stay at a Holliday Inn once....
