Go to rigging
yards, and chat the guys up, tell them what you need.
Was the mast
destroyed, or do you just need the spreaders off it? Does it have a kink in it that can be sistered? You might not so much need a new mast as to have a good repair made.
Sail or Minaret can tell you how much over lap you need if sistering; or Left Brain Stuff. An engineer
can figure it out, a boat fixer like minaret has already done the engineering foot work years ago, and just knows it now.
We've had a boom fixed by sistering, and it is now stronger than new: we're quite content with it.