Re: Bristol 29.9 Mast Boot
On my 31.1, where the mast passes through the partners, there are wooden wedges driven into the gap. This is to stiffen the mast and helps to prevent undesirable bending (like mast pumping when going downwind on the jib only)
On the outside the area is sealed with self-amalgamating tape. There are no leaks.
If you are saying that your wooden wedges are missing, the Spartite kit sounds like a good replacement.
Bristol 31.1, San Francisco Bay