An 87 should still have adjustable timing. Double check that you are on the #1 plug wire with your timing light and if you are you need to spin the motor up so it is on TDC compression and then paint a little white stripe on the front of the dampner that corresponds to the 0 mark on the timing scale. Start it back up and re-check and you should either see your mark or you should see it rotate by. Chances are real good that the dampner has spun, when they first start to go out they usually spin a little and then stick in place and if this is the case then you can paint a new mark and still check and adjust your timing. If it is an advanced case the outer ring will be rotating around the inner ring and if this is the case your white timing mark will look like it is on a damn ferris wheel when you hit it with the light. Meaning that you will see it come up one side and down the other as it goes 'round and 'round.

Mark