The issue of the nose length on the 72 is not really an issue as Claudio can attest because when we build for the 72, we are almost always going from scratch. Consequently, the nose will be in proportion to the rest of the plane.
If the plane is a typical full size stock stunter; say an Impact,Trivial Pursuit etc. where you would normally have a 10.5" nose, a 9.5" inch nose will do you fine on the 72. The main issue is not the nose. If you don't know what you are doing with the 72, the motor can blow your plane apart in flight.