Originally Posted by Bobby_M
I don't recommend what you're proposing because you won't get a stable reading on the sight while draining and you'll also have to plug the top of the sight opening if you want to siphon out to the very bottom of the vessel. You're better off adding new hole and fitting for the sight glass.
I'm not so worried about the draining issue as I have no reason to be reading it while draining (this is for my boil kettle if that makes any difference). I guess the siphon out the bottom could be an issue as I am planning on making a pickup right to the bottom of the kettle.
I can drill another hole in the stockpot that's no big deal but I didn't know if HD would have the right fittings as I was trying to piece the parts together locally.