Mine was the ARF, MKll. I'm a cabinet maker, so the dyhedral was easy. Ran it through the radial arm saw. It only took 1/32" from each side. It might work with sanding, but you want square results. You can do it with a wedge also. Re-inforce the wing bottom, once joined, with some balsa sheeting. Swapping out the engine is no big deal, again, I like to keep it tight to the firewall. I'm a firm believer in keeping this model with an engine around 10 oz. If I were to replace this engine, the Russian made 'Norvell' .40 would be it. Light and strong with .2 more BHP than the new OS.46AX. Joe

P.S. on the mods I forgot to include that I swapped out the aluminum mount for a composit one. Big difference in weight.