Well you could shoot Single Stack if you lose the magwell, and you could shoot L-10 as it is. You *could* shoot open, just don't plan on winning any time soon...LOL. You could also shoot Limited, but with 10 round mags you're really handicapped. Most Limited guns have 20 round mags these days.
If you do the bull barrel, I think you rule out Single Stack...you'd best check the rules for that one.