Starcraft American 15 stringers and transom

I was curious how thick I should make my transom? The one I removed was 3/4” but had another 3/4” piece that only ran up to the top of the splash well. Either I redo it as I took it out or run two pieces of plywood all the way up. My stringers were a length of 1x4 on both sides of a 1x7 that ran down the middle of the boat. I picked up some spruce in 2x4 lengths and was going to epoxy them then place them in and run cloth around them. Would it hurt to go with slightly wider stringers?

 

On both, as long as you rebuild it to at least as strong as when it was new you're fine, anything more than that is to make you feel good, but isn't a problem

 

Thanks for the help i had bought some spruce from the lumber store does it really matter what kind of wood it is if I’m going to be soaking it in epoxy then covering it with fibreglass?

 

Plywood is the best option for wood.