In the case of an electronic, when one of the "fins" on the reluctor is aligned with the pickup (and hence, the ignition is firing), the rotor should be aligned with a terminal on the distributor cap. If not, spark has to jump from the rotor to the terminal every time the ignition fires.

To test, you take an old distributor cap and drill a big hole in the top between the center terminal and the #1 spark plug terminal so you can see inside. Install this cap on your engine. Take a timing light, connected to #1 and use the strobe effect to see if the rotor is aligned with #1 terminal when #1 spark plug is firing. If so, great, you're done. If not you have a phasing problem.

Jim