Well shitballs... Hit a little bit of a brick wall this evening. I got hold of an optical dizzy (Cheers Mike), but it doesn't use the same pattern as the DOHC CAS's. Swapping in the trigger wheel from a DOHC CAS doesnt work either, as the distributor spins clockwise (relative to the sensor), and the CAS spins anti-clockwise (again, relative to the sensor).
I tried flipping the disc over, but this also doesn't work, as the location of the two optical sensors within the dizzy aren't in line, and would also have to be reversed, which isn't really possible. They're not even the same between the CAS sensor and the distributor sensor, which they would ideally need to be.
Even chopping up a dizzy and welding a whole DOHC CAS to the end of it wont solve the problem... Hmmmm Not too sure what to do here.
Should have gone twin-cam, hah :).
I wonder if I might be able to sort out some sort of triggering system directly off the crank and cam, like the later model motors, that copies the mitsy pattern:
Hmmmmm, twin cam eh.... Or I could always throw an aftermarket ECU at it, but that's the easy way out!