The .38/.45 has been around for many, many years, and was quite popular in the late 60's and 70's. It's not a new idea at all. RCBS and others sell the dies for forming the brass and loading the ammunition.
Going to .32 with the .45 acp would be difficult, given the short length of the case. The shoulder would be very steep and there wouldn't be enough neck to hold the bullet during cycling of the action.
I regularly form .400 Cor-Bon from .45 acp brass and still get a wrinkled case once in awhile, especially if using fired brass. It's not so bad with new brass, if you use thicker brass from Winchester or Federal.
Hope this helps.
Fred