A 7/16" spark is a tad optimistic on that system. The factory manual calls for 3/8" with a needle-pointed gap. I agree, first step is pull the flywheel and distributor cap. You probably will find it a mess in there if it has been neglected all these years. It has an anti-reverse ring made of silver wire (keeps it from running backwards). That must be sparingly lubricated with some EP grease where it rides on the crankshaft. If neglected, it wears out and the resulting silver dust fouls everything.
Breaker point gap is critical. Should be exactly .010" (.012" with new points). A better way to set them is with a continuity meter. Turn adjusting screw in the direction to close the points as indicated on meter, then turn to where they just barely open as shown on meter. Then continue to open them 6 clicks (the screw clicks as you turn it).
All wires should be checked. Distributor cap must be very clean inside, and no carbon tracking or cracks. Spark plug wires should be checked for continuity. They screw into the cap--don't pull them out. Put some grease in the cap's towers.
Make sure the coil is not cracked. If it is running, the amplifier is working.
Extremely important!!! Battery and cables MUST be in good condition and battery cables MUST be shiny bright and clean and tight. Failure to do so will result in alternator and ignition damage ($$$$$). NEVER, EVER disconnect battery while it is running.
That motor was state of the art when designed. But it requires TLC.
