I don't know what's the best method to do what you are asking -- except that MANY folks remove the original grips
specifically to preserve them in their pristine state.
I can tell you that I removed the grips from my then-new 686-3, but that was just because I grew up in the 80's and back then, all us mullet headed guys used a Pachmayr black rubber grip with finger grooves.
My original 686 grips have never been mounted on a revolver and fired, unless the factory had them on for a test-firing.
The original L-frame Magna stocks just seem to leave a lot to be desired in a comfortable, ergonomic grip, in my opinion. That doesn't make it fact, but it's an opinion that many share.
I don't think those grips are all too hard to find. So while I don't know the best method for preserving your grips AND using them, I think your best bet is to find another set just like them in a used bin at a gun show, and remove yours and store them.
You bought a great revolver.