Have You considered getting a 3D printer

There has been a bit of a pause on this thread.
There is an openscad file by buffcleb on Thingiverse for an index plate that is fully configuarble for size and hole patterns, even mountings. Just had to have a play with it.
I didn't want to try out a 5 hour print for a proper plate but then thought the best way to make a specific prime is often to start with that number - rather self defeating though in the old days. However a single row could be printed rathe more simply (hour and a half). As an experiment I have printed a 73 hole plate quite thin that could be mounted on an aluminium carrier plate perhaps. I don't actually need to make a 73 gear but this is proof of concept. 100mm dia or 4in for a BS0 dividing head, the holes just fit in. Still on printer so will need fettling. The holes are all the same just poor photo.

Spurred on by this thread, and an Amazon voucher from my employer for Christmas, I finally bit the bullet & invested in a Sovol SV01 printer. It only took a matter of days for Mrs Dave to go from "and what are you going to use that for?" to "magic has entered the house!".

After printing a few tool and collet holders from Thingiverse, I tried a dial gauge holder: not only is it too big for my dial gauge, but it didn't fit the QC tool post either... So, out with the CAD, measure up a standard Myford tool holder and a few hours later, this appeared:

The gauge is a nice push fit and it fits the tool post as-is. It just needs the screw for height adjustment (I printer an M5 thread to see how effective this would be.

Chuffed with the result!

Dave