OK

.. don't get scared..

the NSS is the gear selector sw [ Neutral Saftey Switch]
ATA is the alarm system . That is the K38 relay and it is behind the speedometer panel.
As I stated before , in order for the starter to work the power has to go through a chain of parts that are wired in series , meaning any part in the chain can stop the power .
The chain is power "to and through" the ignition sw when turned to start position.. you have established this .
That output wire from ign sw now goes to the K38 relay . This is a starter lock-out relay for security..the power has to go through this device and continue on to the NSS . That is there so you can not start the car in gear. So, in P/N , the power goes "Through" the NSS and goes to the terminal I had you jumper to on the firewall.. which we have concluded from the original test that form that point on, the starter circuit is fine

So , you have a broken link between the ign sw and the firewall terminal and each part in that chain has to be checked for continuity.. that is the info in my last post explaining how to jumper each component with the terminal#s and color codes according to a schematic up on my board as we speak..
I would start w/NSS , as they are common age related failure part.

A PS note
Because you have the ignition out, I would verify the start portion of it with the 12v test I posted before ... simply b/c when you jumpered the ign sw, you may not have had the gear selector in P/N , compounding the problem...a 12v output test of ign sw [ rather then the simple jumper] will verify this important step..