74 Duster won't start

make sure its in neutral and put a big screwdriver across the starter relay terminals ...(the big ones) ....if still nothing .....then I would look into th starter

if it does turn when you jump the relay then it could be a bad relay or wiring (NSS) back to the ignition switch.

I have never had a bad ignition switch in all my mopar days but I have had starters and relays go bad ...not saying its not your switch but I would look at the starter and relay first. could be wiring issue too.....but you will know more once you rule out starter and relay