Hey cannonball, nice bird. I have put 3003's through out the plane with a six volt sub 'C' pack and they pull everything fine. I have a brand new old G-23 in it and it pulls it very nicely. One thing on the fuel, Kikki Sommerzini once said that if you use Aviation fuel in a gasser you will have a most dependable engine.
Now, before everybody jumps in and claims that they have never had any problems running pump gas, let me say that it is still cheaper than glow fuel and it is of the highest octain and worth the investment. I have also run pump fuel but the aviation is still the best.
Just a note on the 2.4. Those who advise not to use it on this plane are right. It is way too much for it. There are no provisions for flying wires and it could over speed the plane.
It is yours to do as you wish but you did ask and there are those of us that have done this for a long time and do not wish to see you destroy your beautiful bird because you wish to fly it fast. It wasn't made for that in full size and certainly not in the model.
By the way, I use to live in El Reno about forty miles west of OK city in 1980. I drove for Dolese concrete. Big outfit.
Here are a few photo's of a stearman I am working on. bird.