Do the lefties a favor the next time you update your instruction manual. I shot 5 rounds with my newly converted Mossberg 500 for the first time and noticed that the safety lever tore off the skin of my grip hand. When I got back home, it was easy enough to figure out that a long 3/16" allen wrench is necessary remove the bottom bolt and take off the grip (taking care to prevent the compressed spring for the lever from popping out), reverse the lever and reassemble the grip. Unfortunately this was a painful lesson for a 5-minute fix.
I posted a question that I think relates to this. Since you've been through the leg work of reversing the selector and you've seen the internals on it, do you think it would be possible to swap in other AR-compliant safeties? I'd love to put a short-throw safety on my gun but I'm fairly ignorant when it comes to the AR platform in general; I don't know if the internal mechanism on the BU assembly works the same as a true AR (given the linkage bar that connects the exposed trigger to the shotgun's internal trigger).
Specifically, I'm looking at the following item: