I would like to 2nd Kevin Cook's reccomendation, Involve your sailmaker from the beginning.

I am doing something similiar on a smaller scale. I am turning a broken Marstrom A-Cat into a mast for a F14. I talked to my sailmaker from the beginning and his help has been invaluable.

Also be carefull about using Marstrom A-Class Mast's for scaling. They are much thinner and stronger than anything a homebuilder would be able to create. In cross section they look like thick paper.

A mast for a C-Class or an RC-30 would be a better starting point for what you are looking for