Thanks for the quick reply and valuable input. Here are some details that may help us find the perfect solution.
1: Yes, the distributor has a broad range of rotation and is on a gear, so I can get the sensor very close to the ideal location fortunately.
2: When I machine a finished cover, I will allow plenty of adjustment to move the sensor in and out, as well as flats to tighten the jam nuts.
3: The sensor is a M Mhall 437 which is described as a magnetic hall that is triggered by the south pole of a magnet. Below is a link to the spec sheet from Milspecwiring. I am using the magnet they spec for it.
https://www.milspecwiring.com/DATA%20SHEETS/RG/RG_SPEC-0064%20MHALL%20437.pdf
4: I understand the benefits of having the trigger wheel as large as can be accommodated for the sake of accuracy, and I may be able to double the radius of the magnet wheel when I make my final parts.
When you said the M400 has trouble with "two on top of each other", can you elaborate? Do you mean both crank and cam sync signals? (The crank signal is at 90 degrees BTC so these should not signal at the same time, if that is what you are referring to.
Thank you very much for your continued help.