An important missing detail is whether or not your 1989 car is a turbo.

If it's n/a, it really doesn't matter how you install the distributor. The computer can and will make the timing right no matter how far you rotate you distributor.

If it's a turbo, the timing is not computer controlled so it's important that you set the timing correctly by old fashioned methods.

The nonsensical and wandering timing mark usually indicates a slipping harmonic balancer (crank pulley) where the rubber insert has began to separate from the 2-piece pulley assembly. The timing mark (on the outer pulley) is then allowed to "wander" around the inner pulley, which is bolted directly to the crank. If it's an n/a car I would not worry about it (so long as the pulley doesn't wobble or is about to completely fall apart) since the timing is non-adjustable anyway. If it's a turbo car, you would have to have a reliable timing mark to make sure the car is timed correctly. But even then, if you made the appropriate marks before removing the old unit you've probably got it good enough.

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Matt L. -- Cary, NC -- '91 740 wagon