Help with my '68 please

[fourspeedwagon]

I'm have a problem with my suburban-
Sometimes when I turn the key, nothing happens. No click. The dash lights come on, the headlights will come on, the battery is charged. It'll start if push started and I was able to jump the solenoid and start it once also (when I didn't have someone to push start it). After I got home, I went to try and diagnose, but it starter by the key just fine.
1 - battery seems fine.
2 - key switch makes the dash light up so it's working to some degree.
3 - starter did spin when jumped and sometimes with the key.

Truck has a 350 with hei, manual trans, and has been quite reliable for the last 6 years-- not a new build..

Any thoughts? Thanks