You are correct about the Bird Cage. The Earps also came in from the wrong end of town. coming in from Benson, they would have come in form the other end of town.
The one rig he wad on was a Huckleberry rig, and I believe he was wearing a reverse butt on his right side, both of which would facilitate drawing from the seated postion. My understanding is that Val spent hours upon hours practicing with his guns.