It is amazing!Never heard of this done. The breech face of a 9mm is different size then .45 GAP, hence different height of ejectors and i believe because the calibers are different sizes the angle of ejectors (looking down at them and from behind) are different.
Heck, try it out! I do know guys who run conversion barrels from .40 to 9mm and they work but issue was reliability and consistency which caused them to install 9mm ejectors.
Let us know how it works out...my curiosity is peaked...