You guys are right. I forgot about the GZ not having an off setting.
Like I said, it's been a long time
There isn't too much gas in the float bowl, so don't feel like opening it is going to suddenly result in a rehashing of Noah's flood. It's going to spill out, but it's only a couple of tea spoons full, if that.
Leaving it in "run", as suggested, would be the best thing to do. When in run, gas only flows when the engine is creating vacuum. When it's off, you'll only lose a drip or two to gravity.