One bad factor those are made of aluminum, then you put them on SS Pot shafts of the excalibur your going to have a problem when in contact with saltwater/freshwater. Galvanic corrosion. I've done experiments with a friend, making scoops out of SS and aluminum, over a period of about 3 years corrosion set in and the aluminium starts to flake and becomes very weak & pitted.
Very nice looking but My opinion use the stock knobs or some Anderson after market knobs
These were made by a machinist in Ohio several years ago, I don't believe they went into production.