I think the one you need is $30-35. You may be able to do it for less.
The optical part of the trigger is included. It's in the middle of the pic towards the bottom. What you need to make it work is a small bracket that bolts inside the distributor and the shutter.
Before buying the whole kit I would call Crane and say you are moving the ignition to a new car and could they sell you just the bracket and the shutter.
Their tech support is very good, and the instructions are available online as well.
http://www.cranecams.com/pdf/90002000a.pdf