1965 Dodge Dart GT will start in neutral but only sometimes in park

The switch IS adjustable! It compresses an O ring which might be hard to see. Turn it 1/8-1/4 turn more, which will just compress the O ring a little more.
I'll try again, I couldn't get it to move first try...I think the o-ring has hardened over time, the tranny is rebuilt but sat for years, or I may just try a new switch if that doesn't do the trick. Thanks Bewy, at least now I know what I'm dealing with.