Feel free to ignore as this isn't really answering your question, but why are you replacing it? It looks in decent shape in the picture. It also looks very similar to the bulkhead/chainplate setup on my old C36, so I'm suspecting you are replacing due to some rot
just below where the chainplate passes through the deck
. If this is the case, and the area of rot
isn't huge, it's unlikely you need to replace the entire bulkhead.
Mark and cut out a rectangle a little larger than the rotted area and pop in some new marine plywood
cut to the same dims. You could epoxy
it in place or add a bridge plate on the backside that looks to be inside a storage
compartment. Cosmetically, you could play around with stains or oils on some scrap ply to roughly color match the existing bulkhead.