It will depend mainly on the fuel uplifted and the prevailing winds. Assuming a max uplift, that would mean 16270 Kg in the tanks. Using and average fuel flow of 2500 Kg/hr, that makes the endurance about 6:30 hrs including your reserves. A Cruise speed of M .79 gives an appx TAS of 470 Knots. So in still air, you have a range of about 3060 NM. But in real life you would need to have fuel for your alternate, holding fuel, contingency etc. So i would guess you could get a range of about 2500-2600 NM in a -800W with the parameters you mentioned.
Hope this helps
