Zach,
i will I’ll be at the boat this weekend wiring the lights and speakers in the headliner. I can get you exact measurements then. I do know that the beams were laminated separately using the old beams as the guide for the height (not the width though), and to get the placement of the hole for the mast wiring.
after seeing and participating in it I would say that it is a very doable project. But nothing was bonded in place so if yours is that would make it a challenge.
Bryon