I don't normally answer my own posts yet it is a quick way to add to the Forum.
If you use your old bulkhead as a template, you may just add insult to injury. Remember after years of having the mast pound down on your deck, using a previous bulkhead as a means to replace it might not be in your best interests. Get the exact pattern from the Manufacturer if possible.
If there is even a hint of rot in your bulkheads, you are just repeating a shrunken version of that piece of wood (or Mast support post). Using someone else's bulkhead as a pattern won't solve the problem either.
Catalina has built their rep (as well as Hunter) by pleasing their clients.
By all means, fellow sailors, if you have to go that far to replace a major structural member, make sure it is exactly what the builder designed it for in terms of dimensions. Anything less would be not only a waste of time, but a compromise to your safety on an overly flexing coach house roof, imho.
Regards
Fred