Either keep it rusty but seal it to preserve or remove rust.
Removing rust is either chemical or electrolysis.
I have cleaned rust off old tools by electrolysis and they go back to clean meta. You then need to seal them as they will rust again. Try phosphate coating?
I used a spare Yuasa battery from my golf trolley. Make the bolt negative and use a large nail as positive.water with washing soda(salt would do). It will fizz a lot. The surface turns black but brushes off with a toothbrush. You should see nice clean bare metal.
Don’t let the nail touch the bolt.
Well ventilated room.
Frost auto might be worth looking at for electroplating kit but not as cheap. www.frost.co.uk
As for mounting....how about fixed to a framed photo of a Royale?