Re: Dry rot in starboard bulkhead
I also thought about those options, but ended up using a high end oak cabinet grade plywood. Plenty of strength and easy to find. My logic was that if I keep the wood dry the more expensive okume or mahogany would not be needed. Less than a sheet is needed to do both. The only problem I had was a previous owner had epoxied over theh retaining bolts.
Hint: Remove the toilet roll holder to access the retaining nuts for the starboard side bulkhead.
As for original material mine had a mahogany veneer on the outside. '78 model