I always thought you could get a P-40 ish look if you changed the shape of the tail feathers and wing tips. I'd probably hang the engine upside down and make some sort of cowl. I've got a kit I bought probably around '92, and this is exactly the sort of thing I was thinking about, retracts and all. I've seen some done up in olive drab with D-day stripes and you can see the potential. I just figured the retracts would probably take a lot of work because of the wing design. I'd probably go with the .52 myself, my dad had one and flew it with a Saito .50, and that seemed to be a good combo, it's not a 3-d plane so the only thing you'd get with a larger engine is a couple of MPH and a better straight up climbing if that's your thing.