No Dumas's here, monsieur...
Early style race tanks were mounted with a leather or aluminum strap running down a shallow groove in the top of the tank. We could provide for the same style and an aluminum strap so that the tank could be secured from theft and buyers could replace it with a leather one if they like that style better. Or we could just use the factory style mounts.
The mount has nothing to do with the filler style except for placement. With a strap running down the middle, the filler gets shifter to one side. As far as the filler is concerned, an early style Monza type makes the most sense, with a separate vent. Trying to put the recess for the stock filler into the tank will probably require another set of weldments.