Find me a picture of any orchestra pit in the world where someone is playing left handed. I would love to see the person next to them taking a bow to the neck. You would need a whole section of them and have to isolate them from everyone else.
Just saying.... no one in an orchestra pit is playing a left handed instrument, but there are plenty of lefties playing the instruments. It is really only guitarists that seem to glom onto the idea of a flipped over instrument.
There are a lot of quasi-pseudo-science-nonsense posts on forums that claim a heavier block will create more sustain. You are chasing ghosts with that stuff. A good setup on a good instrument is all you need to worry about.