With a P68SC on the way, I decided I'd try and come up with a new gear set-up to accomodate both that and my 8.1, since I couldn't bear to leave that behind.
Most of it is actually just recycled from my rig, save for the Viper MOLLE belt.
I stitched some elastic into loops to the inside of the top pocket in an old hunting vest I had to hold my 10rds (inspired somewhat by the TF2 Sniper), then used an Allen shotgun belt as a bandolier for my 12g's.
It works really nice in practice, doesn't sway like I thought it would, and I can reload the Tib one-handed because of how everything is positioned (keeping the P68 in the offhand).
EDIT: In my constant and unrelenting temperamentality, I'm already looking for a way to upgrade/replace this rig. I'm thinking lose the shirt and get a MOLLE bandolier.