Not likely with that much rust damage on the operating part of the stanchion tubes, you'll never keep the oil in them. Rust is the result of iron that was once in the steel and has since turned to dirt. Remove the rust and now you have pits in the surface where oil can pass the seal. No re-plating can be done seeing as they were never plated to begin with. Rear shocks are likely to have suffered a similar fate.
I'm pretty sure that all conventional motorcycle fork tubes are chrome plated.
Zinc and Nickel are the economical option to Chrome Plating and commonly used on machined steel like hydraulic cylinders and steel bolts where additional protection from rust is required. Chromium metal is typically alloyed with the base metal itself to produce stainless steel. Chrome Plating as a process is an expensive highly toxic environmental disaster for manufacturers and chrome layered on the surface of machined steel is prone to peel off in layered chunks like on the brake drum of an old Bultaco. I'm pretty sure based on the typical wear patterns and rock damage repairs that I have done on dozens of motorcycle stanchion tubes over the decades you are looking at mostly Zinc coatings.
You might be pretty sure, but I think that you are not correct. Chrome has been used on fork tubes for decades...
Alloyed in the steel, not on the steel as a coating. Fork stanchions do not need to be made from really hard material to begin with, trials bikes are all aluminum stanchion tubes now, they ride on nylon coated bushings and a thin layer of oil, Take a file to it or look at the stanchion under a microscope, you won't see layers you'll see worn steel with fine scratches on it.
The topic is about fork tubes for a 70's Yamaha 650. Don't try to muddy the waters with references to current trials bikes.
Might be good to go with some later, more advanced front forks. It depends if you want to keep the original/period look of the bike. Keep us posted.
What do you call expensive?
