problem with dual point no spark

You didn't set the gap as the DWELL setting did you? Below is right out of the '70 Factory manual, for 440-6, dual point. Point gap .014--.019", this is to start with, and should be set "with dwell"

In fact after I changed about 5 sets of points "back then," I hardly EVER used a feeler. I just jacked them open "by eye" and then set them "on the starter" with a dwell meter. Sometimes, you have to jack them because dwell sometimes changes between "on the starter" and "running"

dualpoint.jpg