If that does not do it.......
Get yourself  a 74  service manual.    In leu of that  I created this reduced size wiring  section of the  manual,  but I recently discovered it might have a flaw.  But  it is fairly complete
https://www.forabodiesonly.com/mopar/attachments/74vlwirings-pdf.1715779008/
For everything EXCEPT  wiring,  go over to MyMopar and download the 73  service manual.
Service Manuals – MyMopar
Also there, download the  two page  aftermarket wiring diagram for 74.  I do not believe, however, that it  shows the seat belt interlock stuff.    Those diagrams tho, can be easier to follow
Wiring – MyMopar
The  electrical  path for the starter relay is follows:
From the key,  in  "start"   the YELLOW  wire goes through the bulkhead connector,  through the seat belt interlock, and over to one  of the  "push on"  flag terminals  of the magnetic coil of the starter relay.  Through the coil,  and out  on  (if automatic)  wire goes down the firewall,  down to the center terminal of the transmission  neutral safety switch  which GROUNDS  in  neutral or park.   If a stick  car,  the wire is fed back into the interior  through a single wire grommet  and connects to the clutch pedal switch.     So that path  pulls in the relay
The contacts of the relay are the  "big stud" which is ALWAYS  hot and connects to the battery.   When the relay closes  it sends power down the  no12 or no10 wire  connected to the "big square"  screw terminal  and down to the starter solenoid, pulling in the starter
Once you  "punch" the reset button,  and if it still will not crank,   put your test lamp or meter on the yellow wire at the starter relay and see if  you get power  with key in  "start."  If so,  move to the opposite  "push on" terminal  and see if there is power there.  If so, the neutral switch is NOT  grounding.   While holding the key to "start"   wiggle the shifter  through neutral and back to park,  listen for a click or other  "try"  for it to operate.
If that  shows OK  and or if you can hear the  start relay  "click" then the contacts are bad,  since you already   jumped that point  (right) and got the starter to crank?