I figured out the issue with the fuzzy, buzzy, intermittent output. Pretty simple. The power supply filter (220uF in this case) has to be close to the VS input, pin 6. As it's drawn on the Beavis site, it's on the power jack, so I put it there originally.
After moving the cap over to the board right next to pin 6 - voila! Problem solved.
I plugged in my trusty Gretsch 5120 and began to have at it.
The amp has pretty good clean tones out of the box. I want to focus on a couple of areas: getting the maximum crunch/grind out of it but still being able to have good clean tones; changing out the simple tone control for something that will offer more variety; and seeing if the 'grit' switch is worthwhile.
Finally, I need to name this thing. It's going to be different than the Cricket, Ruby or Smokey circuits for sure. Same basic idea (and same chip) but different stuff happening in the circuit.