Best quality Daniel Fraser side lever 303 450NE rising bite Rigby (which would need to shoot well with the 75% bullet weight)
I would have said a WR 318 bolt and Royal 500, but I know of no way to improve the above suggestions. I've got a soft spot for side levers and Fraser is my bar-none favorite maker.
-------------------- "If we're not supposed to eat animals, how come they're made out of meat?"