Side dots are either silver or bronze from that time. The finish may or may not be on the side of the fingerboard, so inspect for that detail carefully.
If there is no finish on the side of the fingerboard, I'd suggest using fine white Scotch-Brite and lemon oil or lightly sanding (taking care to avoid the finish on the back of the neck).
If there is finish on the side of the fingerboard, then you should make some other marking there, like white enamel (nail polish is good) or small stickers.