What Tip & TVM would sell you would be more representative of a generic French fowler, but not really that of Tulle Fusil de Chasse French ”˜hunting gun’.
Barrel - It should be 20-gauge, of at least 44+” length barrel, octagonal to round via a single wedding band transition, faceted to 16 flats at the transition for 1-2” before the band.
Stock - Walnut and as light & trim as humanly possible to the point where you would not want to remove the barrel from the forend. Later ones may have the more pronounced pied de vache or curved ”˜cows foot’ buttstock.
I note with disappointment ... that the apparent well made ones posted on TOW, all have maple stocks ... wrong (unless re-stocked here).
Lock - Flat-faced post-1720s contracts, faceted pan.
Ramrod - Bulbous end for the first few inches below the muzzle.
Defintely don’t get one of the import FdCs (TWICE as much wood on them than there shoukd be) but looking around for a good used Centermark FdC will get you much closer, at a better price too!
Or, if you can afford a truly custom build and want a really nice one, contact Alex Efremenko; as he is a noted build of early French arms.