1969 Dart 318 intermittent spark issue

Tough to diagnose without more details like what ignition it has since sooo many have been changed from points to electronic today.
Not only do your hands moving wires make a difference but temp changes move wires and make changes also. I've seen the wires from coil to distributer wear a tiny opening in their casing and ground to the intake manifold intermitently. So the wire warms up and shorts. when it cools it lifts just enough to open the short.
Thats just one of a long list of possiblie faults.
At this point the ballast resistor and even the ignition switch is suspect. These come and go with temp change too.