When converting a tricycle gear airplane to conventional gear (taildragger) The gear must be moved forward and the relationship that counts is the distance the center of the wheels (footprint) is forward of the airplanes center of gravity.

An old rule of thumb suggest having the airplanes wheels center of footprint roughly even with the leading edge of the wing when the airplane is level. This leaves a lot of room for interpratation as the Aspect ratio of the wing (wingspan relationship to the chord) has an effect on this. For a typical trainer the wheels even with the leading edge of the wing when the airplane is in level flight position will work nicely.

If the wheels are too far forward this will tend to cause bouncy landings unless you did a perfect landing. Smoother landings always result with the wheel closer to the center of gravity but the problem here is it will also make the airplane much easier to nose over.

John