Well, I went with the dowels/epoxy and then came back to this thread this morning and saw the Kreg jig tip....not sure why I didn't think of that! I've got 2 dowels in each of the 3 faces and one on the rear face and then a pocket-hole screw in between them. I wish I would have put one right in the center too, but this is pretty rigid as is.
However, now that I've got the base secure I've got a problem with where the hand rail joints with the newel post arm.....what's the best way to get this tight? It appears it originally was done with just some small nails.
Thanks for all the help guys!