I plan on testing with test light and multi meter with the wires on and off. The negative battery is on the alternator bracket and inner fender and are in good shape. Heading to work and will have to get to it this afternoon I hope.

FWIW, I ran into one case years back where the upper bracket that connects to the top of the alternator and the intake manifold and the lower mount all three had enough rust/corrosion that there was no longer enough juice getting through to allow the starter to crank the engine over. This happened all of a sudden when the customers running car wouldn't start after stopping for gas. Dealership had the car towed in. I found the problem after a 'parts replacer' had replaced both battery cables, the starter, and the battery. After testing the new battery, I used a pair of jumper cables to run a different ground from the battery to the block itself. Starter spun over instantly. Solution was to remove the alternator and bracket and clean all the mounting points for the bracket and all the attaching bolts. Have no idea what cock and bull story the service manager gave the customer, because it wasn't my job. I was just another mechanic and trouble shooter that they called on whenever they ran into an electrical problem child.

Got home from work and put it up on jack stands to see what the test light and multi meter do at the starter. I was going to test the voltage after the NSS since I know it has power going to it. Darn thing started with the key on the first try. Was hoping for a no start so I didn't have to disconnect the starter solenoid wires. Took that as a sign and am calling it quits for the day. The switch was tested again for continuity and under 1 ohm is the best I could get. Tight spaces to work in. Got a good test in park and neutral and bad test in the other gears.

testing WITH the wire on the solenoid will put the "load" on the circuit and cause the intermittent current drop which your bypass circuit is going around. A ground issue is also a possibility especially if it is able to supply just enough current to compensate for the bad ground. But I'm thinking more on the + side
Do keep us posted

I tried to find the ignition wire from the starter to the firewall. Yeah, that's going to be a PITA to follow as it's in some wrapped bundle of wires. I am thinking it's on the + side as well since the jumper wire from the fuse box to the starter works every time. I almost considered taking the jumper wire from the fuse box and taking the end going to the starter and putting that on the NSS and leaving the ignition from the column on the NSS as well. Basically using the wire that works and disconnecting the NSS to solenoid factory wire. The only thing that concerns me on that is the connector on the NSS is two wire connectors side by side in a plastic end that slips onto the two tabs (1 connector with two wires in it, trying to explain it easier). Unlike the reverse that is two wires with two separate connectors. I could find a connector that will go on the NSS and snip the factory wires and do it that way, but not a fan of that. What are your opinions on that? I think it would tell me for sure if the NSS to solenoid factory wire is bad.

One thing I haven't seen mentioned is the bulkhead connector. We know how great they were on Mopars, GM wasn't much better.

Also a convenient place to put a test light as you work through the circuit.

Agreed and a great place to lose current

I'll see if I can find the purple wire there. They aren't the cleanest, so I'll have to work at it. Probably not able to mess with it today.

this reminds me of an incident back in my junkyard ownership days.............[1972-1984/5]
one day, my brother was under the hood of his vega, [ ] beating the pi$$ out of something with a big hammer. casually, i wondered over to see what was what with that.
seems he had "found the cure" to his starter issues was to beat on the solenoid..........
i casually told him i "knew a guy" in the parts business.
one junkyard starter later, all was well in the world............
he never did pay for that starter.........[the rat !]

The vegas also had a circuit on the ignition that would shu tthe more off if the oil pressure was too low. HMM thin GM knew there might be a problem with oil consumption NAHHH can't be. OK back on topic

Took it out for a local cruise night last night. Fired right up and no issues. I'm going to not mess with it unless it does it again. Then look at the starter end since it is easier to get to than the bulkhead. Bulkhead is under the brake booster and darn hood hinge is right there too.

have you ever looked at a 73 vega's owner's manual ?
if not, i highly recommend it especially if you are having a bad day and need some comedy to cheer you up !