My wife is a portsider and shoots 1911's adeptly.
Her IPSC gun is fully ambi (safety and mag release) but her Wild Bunch 1911 is an SR1911 with ambi-safety only, as per WB rules in "modern" class.
Saw something in a Gun Digest re: a lefty version of the 1911 on the market again. There was a SS "Portsider" made years ago, but not enough were sold to make it viable on the market.
The April 1984 Guns & Ammo magazine has a review of the Randall "Portsider" The 2013 "Gun Digest" announced the Cabot lefty 1911, SS like the original Randall, but with an upswept ducktail grip safety and a ring hammer.
Not cheap, but if I was a southpaw .....