Missing Lock Down Bolt
I also bought a 1973 with a glassed over lock down bolt. I left it that way in favor of devoting the time and money to more worthwhile improvements like bilge pumps, standing rigging and forestay reinforcement. I do not believe it's worth the effort to restore the original locking bolt because I belive it is undersized and cannot be counted upon to hold back the swinging momentum of a 500 pound keel. If you watch the forums on this subject, there are two divided camps. The greatest damage may come in a 180 rollover which whould probably de-mast you anyway. A 1973 is only worth in the ballpark of $2000.