Very nice Shane, ours has a Pratt 450 in it. We have a BT-13 cowl we plan to put on it this summer. Nothing like having power when you need it. They are still treacherous. We know a fellow that nosed his over in a cross wind on take off with a 220hp continental. He has 2500 hrs in them! One thing for sure, it is hard to get killed in a stearman, unless you start high. They are built like a tank!
We have enough parts to build two more.

Leegscott, When I suggested you widen the opening up I forgot about the box frame inside. It might be impossible to side by side the tanks. Perhaps top and bottom? At any rate, it is going to be a challenge to get them both in and have a happy balance situation.
Good luck, I'm out of ideas for the moment. bird.