Chip McCormick makes a mag called, the Shooting Star. It's probably their least expensive and reasonably priced. At least they were when I bought mine. Never a problem with them, they have been perfectly reliable.
My Sig C3 1911 came with mags that have that little plastic extension on them, however they can be removed by taking two screws out. I had picked up some extra Colt Defender magazine a while back, which don't have the extension on them and they fit my Sig perfect. However since the Sig C3 has a factory magwell either work fine.
Check out Metalform magazines!
they make flush fit mags!
also Colt offers them, which makes sense as how metalform makes Colt magazines.
so buy Colt or buy metalform at half the price.
also Springfield armory makes the same flush fit mags.
It may actually be harder to find a 1911 "true" G I than it is to find flush fit magazines?
Rock island Armory makes a G I model thtas pretty true, and Springfiled armory did, but they discontinued theirs about a year or so ago, now their bottom model is the Mil Spec which has a few extras like better 3 dot sights, lowered and flared ejection port.