how can i get the magnum crank trigger to work without the computer?

Hey guys.
I have put a Magnum engine in my old Australian valiant and I'm running it with an MSD programmable ignition and I carby. Since I have swapped to a solid game my timing jumps all over the place and I would like to try and use the Factory crank trigger. It's my understanding that the aftermarket MSD ones work on magnets but the Magnum ones work differently somehow. Is there anyway I can get it to work without running a computer or is there a different sensor pick up I can use to read Magnum flexplate