Engine bed stringer core material

[drewpster]

I was thinking while I was piling on the work, I would pull the engine and trans and replace the stringers where the engine mounts in my boat. I have seen stringers replaced by cutting the tops out of the fiberglass and removing the core leaving a fiberglass channel. Then epoxy in new wood cores and simply cap the stringers completing the repair. Is this the best way to do it? Or should the whole stringer including the fiberglass be removed. Is wood the best core material to use? If so what kind of wood?