You know, I went through the same thing but with the Kimber 1911. The situation I was in with what i already had in my collection made it a better idea if i opted to go with the Kimber .22 pistol and then just put on a .45 slide on it. I though it would be possible since the Kimber .22 conversion kit would fit any milspec .45. The problem is that since the gun is built for a .22 caliber chances are the frame and or its components are not meant for higher tolerances. Im not sure what the Kadet frame is made of, but id be surprised if it wasnt from billet aluminium as opposed to Steel.
What you want to do is possible if the Kadets frame is on par with the 9mm, best way is to call CZ themselves. Thats what i did for the Kimber. If it turns out that it would work, you might be able to find a CZ top end in the Exchange forum. It might not be as easy as picking up a 1911 upper slide kit but im sure someone somewhere has a CZ 75 in parts.
Good luck.