Assuming your '89 is set up like my '88 (I believe all M103s are similarly set up), the initial ignition timing is not adjustable. As long as the crankshaft position sensor and balancer are installed properly the igniton timing should be correct.

The crank position sensor sends a location reference signal to the EZL module when the radial dowel pin passes the sensor and the EZL module determines the timing requirment based on engine revs, manifold vacuum, and idle position sensor swtich on the KE throttle valve shaft

Just check that the initial timing is in spec after you start it up.

Duke