You've probably already considered this stuff but just a heads up - the blocks of wood that support and surround the tubes will probably be pretty porous if not rotting as that's where any water coming in seeped first. When you do your fill, much of the epoxy may seep into and through the blocks and accumulate along the stringer. It might help to wrap that block first with tape or a layer of thickened epoxy. Stick a little rolled up fiberglass cloth in the holes before filling to keep the epoxy from getting too hot too fast. And also so consider getting a good angle measurement so you have that when re-drilling or the flare will not seat well in the bottom side...
Been there, done that
