The tricky part is to find someone who carries/uses the Glasurit paint - which is still available, but is expensive and - from what I hear- a bit of a pain in the arse to work with compared to some modern paints. Some shops can do a very nice job of colormatching , but if you are planning to enter your wheels into a concours competition, it will have to be Glasurit.
The Glasurit silver paint code may involve a base coat of white, or gold, beneath the color coat, I'm not sure.
The silver R65LS was, I believe "Polaris" (imola-silber) according to BMW paint code info. This meant :
Paint Code
060 polaris/imola-silber for the tank, cowling, fairing color coat
098 clear acquer, high gloss
120 schwarz, matt one of these is the battery cover paint color (matt black)
121 ET-schwarz, matt I think this is the engine/trim paint code ?
My book doesn't show the frame paint code (?) but it seems that a semi-gloss black of some sort would work unless you had to be 100% factory.
I *believe* that all the silver LS bikes were delivered with silver painted wheels (not white, like many of the red LS bikes) but I don't have the BMW paint spec for that.