The problem with doing it like that is that it's hard to determine the centre of the apertures that way, and it shows with your photo there. Your No.5 ladder aperture is miles off centre - both the no.5 one in that vid and the Poole-made one on Frankenrifle come out clearly at exactly 100 yds (the Poole one was tested a week after filming while seeing if the brass cased ammo I'd got would chamber without resistance in its tight chamber). The Faz No.4 rearsight on the right of your photo there also has the datum below centre of the ladder aperture and above centre fror the battle aperture, and I suspect if you shot it then it would come out at exactly 400 yds.Did you think about doing it this way?
You do need two of each sight to make it easy, but otherwise just put the sights onto a common axis pin/rod. This gives you your datum level between the models of sight.
With a micrometer/ laser/ good eyes and a ruler, you can directly find the heights of the centres of the leaf/battle apertures about the datum point - and the relationship between battle and leaf on the same sight.
I did comparisons of most of the sights. Can't find the photos now, but IIRC No5 battles are set to 300, and No4s mostly to 400.
There is very little design info about the sights, and I did wonder whether the "400" chosen for the No4 was because they found soldiers shot low in poor light or under stress (better view of the target, etc).
Actually shooting them at 25, 50 or 100 yds (or further) is the only real proof.
If you get the opportunity, I'd be really glad to incorporate your shooting data in my table - in the meantime I've come up with a theory regarding 100/400yd battle sight zero for the Mk.1 No.4 sights, but I don't want to bias people by saying what it is until I've got sufficient data to confirm or deny it