Since this is your first pump; are you going to re paint it or leave it as is?
If you are going for a re paint, decide what brand you want to go with. Texaco and Standard Red (White) Crown used the large sized pump signs. Those are being reproduced and also available in the correct sized decals.
Some brands didn't use signs at all but decals.
If you are re painting and doing a different brand, weld up the holes while you are doing the body work. For signs- align them on the doors before painting them and drill the new holes. Install them after the doors are painted and dry.
For decals, put them on after the doors are done.