John,
Unfortunately this is more complicated than the points and condenser
ignition and requires a special peak volt meter. There is a long shot try
that may identify the problem easily and that is to locate the rectifier,
disconnect it and crank the engine looking for spark. Beyond this there is
a lengthy procedure to verify the peak voltage from the stator, trigger
voltage, and a pack failure. These parts are expensive items to replace and
most shops will only replace the full electronics package to prevent one
component from damaging another. The wiring is a type of high voltage
insulated rubber that with the age of your motor will very likely be dried
out and cracking causing shorts to ground. If this is the case, you may
have some luck trying to put rubber tubing in place of the dried insulation.
If you live near Kansas City, I can help. Sorry for the bad news.

Don Dando