I will not touch a line with that type of gas cock valve without changing the valve to a ball valve as part of the project.
A couple of years ago I was looking at a home to buy and the bedroom had a strong gas smell. I questioned the home owner who was showing the home and she said, "I am not sure what is causing the smell and I can't afford a plumber so I just sleep in the living room." EEEK! I did a little nosing around and found the leak problem. A water heater with this type of valve in a room off the bedroom. I felt bad for this lady and not being the type to ever walk away from a problem even when it is none of my business, I went out to my truck and got my tools and a new valve. Installed it for no charge. Cost me a little bit but I could sleep that night. I know, I know, we always have to get a permit and inspection but I just could not let this lady blow up herself and her neighborhood.