That's not being cheap. It would be sad to see a brand new usable kettle go to the scrap yard.
Think I picked sight gauge but a ball valve might be better. If the weldless one won't work with 2 O rings then you could take it to a welder and have a fitting welded on. Sure would be cheaper than the price of the kettle.
Might want to start drilling the hole a little higher than the actual spot it leaks from to get it off the bottom more. Let us know what you end up doing.