I went with Hitec HS-81 micro servos for the ailerons, but standard size will work too. The way the fuel tank is installed has nothing really holding it in the fuse. I wrapped it in foam so that it fits kind of tight in the fuse and then CA'd a piece of balsa across the fuse right behind the tank to hold it in place. Check out the pic. Other than that, check the straightness of the fuse to be sure that they built it right. Mine had a twist at the back of the fuse where the rudder attaches. It was bad enough that I couldn't put the tailwheel between the rudder and fin. I moved the tailwheel to a more scale position, but wouldn't recommend it if your fuse is not twisted. Good luck, and let us know how it goes.

Jesse