#23 - 2 holes.
The early cars with the band/clamp style method of holding the headlight buckets does not use these plates being discussed (see replies #10 and #12 on the first page).
I would think that #23 would not have the plates for holding any of the four headlight buckets. Perhaps they were changed out at some point in it's history.
Not to go too far off-track but the plates being discussed were the second method of attaching the smaller diameter (1960 Galaxie) head light buckets to the '67 Shelby's. This was a much simpler, faster and easier way to accomplish this addition/change. As to when this change of method occurred not sure but I do know that car #112 (completed at Shelby American Dec 5th, 1966) has the plates (one hole in each plate) for the inboards and the band/clamps for the fender lights - so some of both at that point in time.
Here are a couple of photos to help illustrate what was initially done. Note this was a very Mickey Mouse/Rube Goldberg way of doing something and a real PITA ! The plates method for both the fender lights and both versions of the grille mounted high-beams (not driving lights) inboard or outboard was a step forward in getting the lights on the cars.