I purchased a full size frame pistol with 4" upper way back. It was not a well done conversion. I corrected it, got it running and let the top end go. It is now a full size gun and runs like a top.
Long story short, not a good idea unless you really know what to do.
The front of the rails on a 4" frame gun are set back more.
The barrel lower locking lugs are shaped differently and the outside barrel is relieved back farther, closer to the chamber.
I believe the slide recoil spring tunnel back face is set farther forward on the slide along with the
grooves in the slide.
The barrel bushing is shorter.
Shorter recoil spring guide and plug.
Shorter, stronger recoil spring.
If you want a 4" 1911, a Colt 1991 is a good price/dollar. I'd go that route first.