If you have never flow a biplane you are in for a thrilling and very cool experience.
I would agree with rcmigpilot. I don’t know much about going electric with the Stearman but I do know she’s on the heavy side and what I have seen large electric planes need a lot of battery, which adds to the overall weight. I would add up the power and weights than compare them. And again you’ll have to figure out a place to put the battery and make sure you have enough airflow over it.

As for me I’m using a Saito 180 4 stroke and I have found that that’s more power than you would ever need for this plane. On the other hand having the extra power has saved it a few times usually on take off.

The G26 seems to be the recommend gas engine, which is equivalent to a 120 4 stoke. If I were to build another one I would use a Saito 150.
I have just got into electric on a couple of small planes and true electric is nice but still, in my opinion, there is nothing that beats the roar of a gas engine.

One more thing I have said this before and I'll repeat it again. As your building the Stearman make sure the bottom wing, top wing and horizontal stab are all at "0" degrees incedence to each other. This was my first biplane and I didn't think about it; and the instructions didn't say anything about it either. I was a few degrees positive, needless to say it was fun first flight.
After your first flight you can adjust the top wing if you feel you have to. Mine are at "0" and it flys great.
Good Luck
Shubova
[8D]