First of all i would recommend you a precision caliper of good quality if you want to measure within those tight tolerances.
then it isn‘t necessary to create a dial according to the A7750 specs but to create a built with:
A) a custom DW/DWO for the A7750
B) custom movement (LWO283... etc.)
i would measure the specs for the cut out on the backplate of the gen dial and then try to use the left over space on the stock A7750 Date wheel to create a matching font.
as you don‘t got the gen back plate for your beautiful dial it won‘t do it‘s thing just to measure the cut out for the cyclops.
Believe me - when it comes to date wheels and matching fonts every fraction of a mm counts.
legend also knows his profession better than anyone else.
the thing with the 7750 is that it is simply not made for this dial layout and the sub dial positions and their function don‘t correspond with a smaller diameter of the date wheel.
the only way i could imagine is to use the bespoken leftover space on the inside of the date wheel (which should be about 0.5-0.4mm) and reprint it while trying to align everything so it won‘t look too improvised.
keep in mind that there will remain other problems with the A7750 and a custom dial won‘t change the specs of the stock DW without resulting in the same disaster as what the stock JFs are.
in the end i would say it will be cheaper to acquire a gen dial and LWO283 + modified new style JF hands or mikey hands according to the dial than designing a custom dial just to handle the abominations of specs of the A7750...
hope that helps.