The model you're talking about has all 1/2" npt fittings. They typically require a 13/16" to 7/8" hole in your kettle to accommodate the bulkhead fittings. If you have this size hole or smaller in your current kettle, then you should be able to take any 1/2" npt bulkhead and ball valve assembly and attach it. I wouldn't necessarily limit yourself to buying the ball valve that Bayou Classic sells. Lots of people sell weldless bulkheads and ball valves. You could try Brew Hardware or Bargain Fittings. I've bought from both and have had good experiences. But feel free to shop around. Like I said, lots of places sell these parts.
I have the kettle in your picture, just without the spigot. I've drilled into these pots before and put all kinds of weldless fittings on them. It's no problem as long as you buy a step bit.
