I'm a Lefty, have been for years.
For fun, not for work, I bought one of the L/H Stag ARs in 6.8mm SPC. Mine has the Ambi selector lever but not the Norgon ambi mag release. I have gotten so used to punching the mag release with the thumb of my support hand that I have never really gotten into using the ambi mag release with my trigger finger.
The L/H Stags are nicely turned out and mine runs. Q/C on it seemed pretty darn good - better than I've encountered from other name companies.
Erick