Not cranking over but will with relay but now no spark

Thought of that .did replace the key before I took of road many years ago because key was worn out and wouldn't engage tumblers..so it's not that old ..will def pull steering wheel to chk tho

The key part is fine. Its the switch itself that I believe is your problem. The internals of this are probably gummed up or corded.

1970-1976 Plymouth Duster Ignition Switch - Steering - Standard Motor Products 70-76 Duster Ignition Switch - 16685-05065742 - PartsGeek