I am restoring the entire bike from top to bottom, every nut and bolt, and I detected very slight play in the cam when fitted into the crankcases, so I thought I'd go ahead and replace the cam bushes along with the many other bushes I'm replacing in the rest of the bike. I now realize that the cam is unique in that it rides on two bushes on each side of the engine, so must be fitted to both bushes simultaneously. Otherwise, the cam might fit okay on the drive side, for example, but bind on the timing side, or vise versa. Thus the need for the services of an experienced machinist. In light of the foregoing, I'm going to leave the cam bushes alone. Thanks to all for the helpful replies.