I converted my Kadet MkII to tail-dragger, had several problems. It will depend on your model what kind of difficulties you may have. First, make sure you can make your tailwheel steerable, either directly from your rudder linkage or by means of a separate servo setup. second, the mains must be forward of your c/g. As someone else said, maybe even with the leading edge, but I had to go more forward than that because mine was prone to ground loop on landing (flip over). You want them far enough forward that the plane can be tail-high on the mains without tipping over while landing, but not so far forward that the tail won't come up before the whole plane lifts during take-off. You may have to experiment to get it just right. Good luck. There are several guys at my field who have successfully converted theirs. Most notable is the SIG Kadet Senior