I'm interested in buying a Commander SW1911, but I already have the Government and I was thinking maybe I could buy a shorter slide and barrel for it... will this work?
Technically, yes. But if you don't need the Gvt, sell it and buy a commander, the frame/slide/barrel fit will be better. Getting a commander slide/barrel to fit properly won't be worth the trouble.
Myself, I'd keep the Gvt and buy a commander if I had the coin.
The Government dust cover might be a bit long, not sure. For the price of a slide. bbl and all the other parts needed you might be better off just buying another gun.
Save up the cash and buy another gun. Like has been said previously, you will pay as much for a quality barrell, bushing and slide as what you can buy a commander size 45 for.
In the late 1990s Auto Ordnance offered a neat little package called the ZG-51 Pitbull, both as a complete handgun and as a conversion slide and barrel for an existing M1911 frame assemble. Essentially, it transformed a regular 1911 into a handgun with an Officers Model-length shorty barrel and slide.
Disadvantage: the conversion package made the gun shorter, but the butt wasn't any shorter than a M1911 [since it WAS a 1911] and some folks found the shorter sight radius to be a disadvantage. advantages, of course, are that it uses your existing magazines and whether short or long barrelled, you still have your same trigger pull.
That was back in the days before lasers on handguns were real common. Nowadays I might think about trying one with a pair of Crimson Trace laser grips fitted. But I've been hauling a full-size M1911 [Argie M1927] around since the first of the year, and it works for me, at least until the really warm summer weather gets here.