I read over your previous posts. You have had your share of electrical issues. Hang in there.
I looked at a 54 wiring diagram and the ignition switch feeds (pink wires) the ignition coil and fuel tank level sensor.
Get where I'm coming from?
The other side of the ignition switch (red wire) connects to "B" on the voltage regulator that you just replaced.
I would make sure the wiring is good (not broken or loose etc.) at the voltage regulator.
If this looks good, check the wiring on the ignition switch.
If this looks good maybe you have a intermittent ignition switch.

When you work in areas of old wiring, get into the habit of cleaning the terminals and connectors even though it's a pain.
This stuff is over 50 years old and needs a little help. A light coating of anti-corrosion, after cleaning, may work wonders.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."