Thanks for the input guys.

Yesterday I pulled the starter back out. Re-cleaned all contact points.

Also load tested the battery just to be certain on that. Battery fully charged and passed fine.

Replaced the solenoid plunger and contacts on the starter. Bench tests fine. Put it back in and no change. Just a solid sounding click but no movement.

I disconnected the small solenoid wire and jumped 12 volts with a separate wire and the starter motors over normally. Guess my next step is to get a voltage reading on the solenoid wire when the ignition switch is on start, but I'm starting to think like Robert mentioned there's something amiss on the ground side.