There are some good ideas here, although if I were to have a start like that, I'd fire her-up , play a bit to see how she operates, look for any damage you would need to fix , and try some recipes.
You're not going to open immediately anyhow, so play a bit.
You Pit will do the work for you, looks like a great work of love in the old school style. Get some good wood and have a reliable source with Good Wood, not Moldy ,rotten or infested with Bugs. Cook in batches , to get the feeling of a busy day and see how long each meat takes to doneness, and the best heat to cook with , for holding and keeping eatable.
The leftovers can always become a different dish, Burnt Ends , Chile , Salads(Brisket Salad is Great) and anything you can think of -or - the Customers suggest.
Cleanliness is a Major factor, as you already know , and a quaint look and service style will bring them in also , Butcher's Paper to serve on... bottles from other sauces re-filled and on the table , Paper towels for each table and anything else you may think of, you're not opening a Fine Food Restaurant , it's a BBQ Shack , make them feel the Old Time excellence of a slower and more laid back Era.
Make them want to stop in, no Electric cookers and no Microwaves A good simple menu and good service does wonders. Too much is a killer...My menu would be:
1. Briskey - Sliced or Chopped for sammies w/sliced Onions, Dill Pickles and a dash of Sauce(Let the meat sell itself.\
2. Chicken , Whole or Halves
3. Ribs and the Tips(these are very popular)
5. Bologna ( a good off the wall seller , and cheap)
6 Turkey Breast
7. a specialty Meat of the area (Mutton?)
and the sides:
and Peach Cobbler for Dessert.
This is JMHO and a list of things I know will sell...
just Please don't waste that beautiful Pit, it begs to make you a lot of $$$.
Wish I were that lucky, I'm jealous . Have fun and as always . . .