Tick-Tick-Ticking Sound - Pinging?

All - I have a base 1972 Dart. Slant 6, 225c.i.

I drive it about 3 days a week into work, and it runs like a top. It had 39k original miles on it when I bought it. Near mint interior, trunk, etc. Engline-wise, my previous owner had just done a valve job and tune-up.

Now when I'm driving I get a discernable tick-tick-ticking sound that increases as I accelerate.

Is this pinging? I use a 93 octane gas in it, but perhaps need an additive.
Is this the valves?

What is this? And how can I fix it?

Thanks for any help here you can provide.