Only using jewelry and cars as experience, I would do rhodium. Chrome and nickel break down faster with oils, but we also aren't talking about 10 quarts of Mobil 1 haha, so I may be out in left field on my reasoning.
Just like every replating, its good to remove the old -- just be careful not to overwork the surface and file down the engraved finish. A liquid solution should be the best I would think
High end gen bridges and other movement parts are generally rhodium plated. Not something that you would normally do in your house. Take them to a professional.
On my last post I should have also mentioned platinum is also used.
White gold is actually just normal gold with rhodium plated on top.
There was someone selling platinum plated Pam rep movements back about a year ago. Maybe you should try searching for that. They also came in some H Factory models that the Cartel was selling. Maybe one of the other members or maybe Angus might know where to look.