I dowelled the saddle gib on my early Super 7 about 20 years ago after reading an item by either GHT or Jack Redford. It was certainly an improvement, and allowed the gib to be set very closely without tightening up when the saddle was moved. Interestingly, Myford changed the gib design on later models so that one of the screws provided the equivalent of a dowel function. However I don’t believe this was carried across to the ML7.
Mike