BM note:
Invert spark A and spark B on MS board so Spark A goes to pin 31 and Spark B goes to pin 36.
(
http://www.miataturbo.net/megasquirt-18/ms2-standalone-stock-ignitor-70414/
).
As you can see, we’re using the natural pullup of the existing LED to drive the base of the new transistor,