I think JE is pretty accurate in his estimations. My nephew took a rockchuck at 1264 yards this spring with his .308. 1263 Yard Rockchuck
But a coyote won't stand around that long. If you aren't too hung up on a .308, you might look into a .260, 7-08 or even a fast twist 6mm cartridge (.243AI??). They'd be adequate for smaller big game species, have better BC bullets available, have less recoil and be cheaper to load for. Just a thought.