Hi,

Since this a point and condenser ignition system you could have a bad condenser.
The condenser is there to reduce arcing of the points. It works like a capacitor in that it charges up but if it shorted the power goes to ground. This would keep the coil from getting current to the primary winding.
A test light will light because it’s still a circuit.

When the point open this shuts off the current to the primary coil.
When this happens that coil will dump it’s magnetic field into the next winding and at the end of that winding is you spark plug. Bingo spark when that high voltage jumps to ground in the engine.

It isn’t a common things to have a bad condenser cause no spark as they are very reliable.
In your case the condenser or capacitor has gone funky. Age is the number one killer as it’s only turns of aluminum film that can corrode internally.

Make sure you have the wires on the points and condenser are correctly placed with insulator washers where they are supposed to be.
It’s very possible that they could cause the same problem of power going to ground and not THROUGH the ignition coil.

Hope this helps.

Phil