Bulkhead Material

[78Hondo Cruiser]

Ok I am new to working on boats and I am much more at ease working with metal but need to build a new bulkhead and some speaker boxes for my 78 hondo mini cruiser. Can you use just any plywood material or do I have to get something special. I have never built a speaker box either but shouldnt be to hard. Any advice would be helpful. I figured I could use regular 3/4 ply for the bulkead and mdf for the speaker boxes and resin the hell out of them. Any other ideas?
Thanks
Kyle

[Dub C]

for spk boxes that should be fine to resin the hell out of them, spk boxes just need proper airspace with no air leaks, and a rigid enclosure, the goal is for the enclosure and walls not to flex or move at all. when they do it's wasting energy into physical motion on the enclosure instead of sound out of the speaker. kind of like a car burning out due to lack of traction, impressive show of force but does nothing to move the car forward.