Dignlivn (10/18/2007),
It looks like no one is able to answer your question about electrifying a Great Planes Slow Poke. That's probably because I don't think it's been done much - yet.
However, I am currently building a Slow Poke of my own (the 3-ch version, not the larger 4-ch Sport 40) with a Rimfire 35-30-1450 motor (GPMG4600), a 45A ESC (GPMM1840), and an APC 9X6E prop. I haven't decided on batteries yet but by the way everyone talks about the inherent tail-heaviness of the Slow Poke design, I'll probably have to put a John Deere battery in the nose to compensate for the light Rimfire motor.
It will be awhile before mine is ready to fly but there's a guy on WattFlyer who's building the same combo and his may be flying by now. (I haven't heard from him in a couple of months.)
Everyone here talks about what a fine plane the Slow Poke is and I'm expecting my electric version to fly just as nice. I'm electrifying my Slow Poke because I don't want my neighbors to lynch me but I do have to agree with RC Ken in that this plane would sound best with 4-cycle power.
Good luck,
Harvey