Crank Sensor

The best I know without certainty is the flex plate sensor is a Hall sensor. They are a 3 wire sensor with open collector output. The output is pulled up with a resistor (4.7k), to 5V or what is required at PCM. The supply is often wide range, if it has internal regulation. Might be best to bench test at 5V, with current limited supply at 50 ma, steel target, output is active low.

Going mechanical advance is a step backwards.

You may consider multi-point injection and electronic advance with mega squirt or other ECU.