As a fellow lefty here's what would make up a true LH gun:
- Lever that swings to the left.
- Front trigger fires left barrel, rear right.
- Stock cast on.
- Rolled trigger guard on left side
I'm sure I've left out one or two other items.
In practical terms all I've ever done is get the stock bent for cast on. A left swinging top lever will actually stop me from buying a gun as I've grown up with right hand levers and find it as easy to push the lever as pull it. I couldn't get used to the LH swinging ones.
Some guns have triggers bent to fit, I've never noticed a problem on triggers bent to fit a RH.
Guns with a palm swell for a RH can be a problem as the grip feels wrong for the LH.