Nice!
Will you be able to line up the long bolt?
A338 has one long bolt that essentially makes the stemfitting impossible to be torn off (without taking the whole nose with it. )
Could say the stemfitting does a secondary job clamping stem to deck together.
Also has the two lower bolts that only go thru the stem.
Our stem fitting is a great design!
The plug/bulkhead you have there imco could be tabbed to the hull to insure the upgrade does as you say: hold everything together better.
Bet you had a great time working up in there!!!!!
Really enjoy your photos and work!