When converting a trike geared plane to a tail dragger, a good starting point for placement of the main gear is to have the wheel axles directly under the leading edge of the wing when the plane is held level as in flying attitude. Get them to far forward and your landings will be difficult, lots of bouncing; and take off directional control will be more difficult. Get them to far aft and noseovers become quite frequent, especially at low taxi speed but directional control is much easier. Also, give the wheels a slight bit of toe in, about 3 degrees, to make takeoffs easier.