Need help finding a 7/8 inch plug for boil kettle.

Buddy of mine gave me an older brew kettle that has a 7/8 inch hole where the ball valve was connected. I took the pot to the local hardware store hoping they might have a ss plug I could use but they didn't. They suggested using a rubber plug/stopper but I thought that would affect the taste of anything cooked in it.

Anyone have any ideas on what I could safely use to plug this hole and where I might find said item? I would like to use this kettle for BIAB sessions on my stove top and I don't need the ball valve for this.

looks like a standard hole for a standard 1/2" bulkhead.
bulkhead and a 1/2" pipe cap.