Flat back points to a staggerfeed LA...and stocks seem to be fairly easy to find, depending on what you want.

I have a Boyd Ross FT on a flat-back 110 and it works great; if synthetic is more your speed, Bell & Carlson makes the Durmaxx, Medalist sporter, and Carbelite, for the staggerfeed long action.

You can make a centerfeed LA stock (like the laminates Stocky's sells) work with a staggerfeed LA, you just have to do some dremeling to the mag inlet and shim the L-clip channel and/or bed it.