Not quite the same problem, but I have always thought that if vibration is a problem you are better off bracing the lathe at the top, not at the feet. I do a lot of biggish bowls from logs and although converting to a variable speed drive has helped a lot I still brace my floor standing old Viceroy by clamping it to the wall, and to my metalwork lathe.
Fixing the feet must induce a lot of strain in the structure and cannot be as effective.
John