I am working on making a crank trigger mount that will work in the factory location and use Holley 554-118 hall effect flying mag pickup or pretty much any 3/4" thread sensor. ATI will also build a new balancer that will include a built in12-1 magnetic trigger wheel. I believe they can build the balancer with up to 24 magnets in it too. I will post pics of pickup mount along with part numbers from ATI. I am going to have the pick up mount copied and produced, I actually can't believe that someone hasn't made it yet TBH.
I was also considering having a bolt on 12-1 trigger wheel in the Buick 6 bolt configuration made with a lower crank pulley that would allow you to use the factory accessories. I would have to see what the interest is in that project first since ATI offers a balancer with a trigger wheel and lower pulley in int or ext balance that is nicer than any other balancer offered for the Buick.