No. It's not...everything is possible..
Go with that ^. The GSG 1911/22 is accurate, fun, cheap to shoot, and 100% feels the same in hand as your Kimber. Plus, they're purdy.for just a few bucks more, you can get a dedicated 1911, in .22 caliber. I got one of the GSG 1911's. It's well made and same weight/controls as the real 1911. Whatever works for ya...
The 5" will work on the 5". One may be able to get one custom made. I don't recall seeing one made for the 3" yet.
I think you meant the 5" conversion will work on the 4", which is true. They are the same frame. I have the Kimber conversion and have been happy with it. My only complaint is that it doesn't hold open on the last shot. Not sure if the GSGs do?