I disagree IF---- you stated that you have 6V at the coil when cranking
NOW THIS IS IMPORTANT----
How did you "crank" the engine?
IF you measured the coil pos. "cranking" while jumping across the starter relay, you will be reading through the coil resistor-- a meaningless test in this case
BUT IF you measured this 6V at the coil while using the key to crank, THIS IS NOW WHERE ENOUGH voltage.
The battery should be ABOVE 10.5V when cranking. The coil should measure NEARLY the same, maybe 1/2 volt lower
HERE IS WHAT I would try, if you did measure while using the key to "crank."
Take a clip lead (from Radio Sh$$ if nowhere else) and jumper TEMPORARILY from the big stud on the start relay directly to the coil positive.
Now see if it has spark, and if not, confirm that you are getting ABOVE 10.5v at the battery when cranking.
So far as "setting the gap by eye" this isn't gonna cut it. I stated somewhere else that I suspect these pickup coils lose magnetism. Some of them seem pretty critical. The problems with the reluctor are:
They call for .008 which 'ain't' much. If the dist. is worn, this can cause a collision with the reluctor. Also, when the vacuum advance moves, that gap can change--for the worse.
Yet another way to check for the voltage problem is to "bump" the engine until it's around halfway between reluctor "tits." Then "normal up" the system with the cap off and the key on, or better yet with your clip lead from coil + to the battery.
Now with the coil wire close to ground, grab the rotor and "snap" it smartly against the advance springs. Look to make sure you moved the reluctor "tit" past the pickup center. It just might generate a nice big spark