As a lefty shooter myself I really like my Winchester Wildcat. The safety is reversible, mag release is ambi, has last round hold open, and slide is releasable from one side with a button and the other by pulling the bolt back. Weighs 4lb with the plastic stock. Also available in a wood stock that's a bit heavier but would be easy to shorten the LOP on that one. It's still right side ejection but as long as that doesn't bother you I'd definitely give that a look.
Ruger makes a dedicated LH 10/22 as well but it's one of the more pricey models.
Savage MK2 might be worth looking at too. Bolt action, not semi, but available in a proper LH setup, reasonably light (5.5lb ballpark IIRC) and has a shorter LOP.