Buying what fits and feels good is the bet advice.
There as so many Quality O/U's to choose from. Browning, Beretta,H&K,SKB,Weatherby etc. Handle a many as possible then decide.
I'm lefty also , most O/U's come with nuetral cast today and opening lever is a non issue as well as the safety,they are easy enough worked by either right or left shooters. If you need some cast on the stock can always be bent buy someone who knows what they are doing and stands behind thier work.