Starter won't engage when key is turned.

Jacked the car up today and put her on jackstands.

I forgot to mention this earlier - I have an early 63-66 A-body with a 71 slant and a later model A904. Based on my web research the later model has the 3 prong male. When we did the motor/trans swap a few years back (a friend helped me), I didn't recall hooking up the NSS, and since I was (and still kinda am) a noob at all of this, I think to just get the motor to crank, my friend grounded the prong on the relay to the motor, bypassing the NSS. He warned me that I wouldn't have backup lights but not super sure he knew to ground it via the NSS.

So anyway, after I jacked it up today, I poked my head under and confirmed that it's a 3 prong male switch. And I also confirmed I don't have anything hooked up to it. So that's something I plan to remedy, as well as the backup light switch for my aftermarket B&M Starshifter.

But I wonder: is this the problem? If my NSS prong on the relay is already grounded to the motor, shouldn't it start up?

The relay as mentioned before, is still fairly new. Could the problem be with the ignition switch at the key? How would I go about testing this?



[To complicate matters, I swapped out the old positive terminal cable for a new one. The insulation was cracking on the thick wire that goes to the starter so I figured as long as I put everything back the way the old one was (large wire to the starter, smaller wire to the relay), it should at least crank if I bypass the relay. Instead I got a click on the starter. I tested the voltage at 3 spots: 12.25v at the positive terminal on the batt, 12.25v @ the positive IN on the relay, and 12.25v at the starter solenoid. I know, I know, I should learn to fix a problem before I create a new one. Any thoughts?]