OT: Difference between Epoxy vs. Fiberglass Resin

[BRENT in 10-uh-C]

I am working on a set of reproduction Top Iron Sockets that need reinforcing inside. My 'go-to' epoxy company for the past 5 or so years has been TotalBoat by Jamestown Distributing which I have been very happy with their products. Several days ago I called them to ask for recommendations where I plan to insert a 0.750" aluminum rod into the top socket and then pour Epoxy into the socket surrounding the aluminum rod as a method to reinforce the socket and keep it from bending due to the weight of the top.

After a lengthy discussion they asked if I would send them pictures of what I am planning and what materials. One of the tech guys (Brian) called me back yesterday and said "After some thought, they do not offer a product for my needs." Apparently what makes 'epoxy' strong is it being able to soak into wood and that penetration is what makes it strong. Naturally I can fab a piece of 18" long piece of wood to insert however that does not allow the epoxy to soak into the metal Top Iron Socket which he claimed is what will make this strong.

I began wondering if using a panel bonding adhesive would be a good solution for this but I understand those adhesives are very flexible when they are dry, ...which is not what I am after. I need rigidity. So what are some thoughts on the best product to use when trying to pour into a socket that will give rigidity and reinforcement over the 18" long area? Should I just use Fiberglass Resin??