Forget the 0 MOA mount and use the 20 MOA mounts. The 20 MOA mounts will keep your scope from running out of vertical adjustment when you try to dial in a 1000 yd zero.
Use the 20 MOA mounts and find some rings that put the scope objective bell about 1/4 of an inch from the barrel. The specifications for rings will list the distance from the top surface of the scope mount to the bottom of the scope tube.
If you can brace the rifle so it is level, you can place 2 equal stacks of pennies on top of the mounts and rest the scope on top of the stacks. Add or subtract pennies from the stacks until you get the scope objective bell 1/4 of an inch from the barrel, then measure the height of the stack of pennies. Buy rings with the same height specs as your stack of pennies.