I'm making 2 sets of floorboards, for my 28 Phaeton and my 29 Tudor. The boards vary in width from one board to the next. Not only do the boards vary in width, but the same board can vary from one end to the other. I'm copying a set of original boards, which are Maple. The Ford blueprints call for "NO THROUGH KNOTS, AND NO EDGE KNOTS". That's what the prints call for, but it wasn't always followed, because I have seen a couple of through knots.
I bought some nice Maple boards from Menards. Finding the exact router bit to make the correct tongue and groove took some searching. I finally found the router bit at a used tool store.