With what rifle and load? And does your scope have a Milrad or MOA reticle?
You can figure it out easy enough. You need to know the BC and velocity of your bullet and plug it in to ballistics calc along with enviro conditions, etc. It will give you your drops in MOA at whatever yardage increments you choose.
The configuration of your scope is the next consideration. With 65 MOA of travel, you will have probably about half of that for up travel - 32 MOA. If you use a 20 MOA base, you can gain another 20 MOA for a total of 52 MOA. With a 65 MOA scope, 30 MOA bases would be ideal, giving you 62 MOA or so, and the ability to use all of your scope's travel. If you were shooting a .7 BC bullet @ 3000 fps you could zero out to about 2100 yards @ 1000' elevation.
My Scopes have MOA reticules allowing an additional 30 MOA of holdover. If your scope has a similar reticule you can add whatever it is to your range.
I am considering S&B 5-25x56 PM II/LP on SAKO TRG .338 LM which has 65 MOA.
If you set it up with a 40 moa base so you can use all 65 moa up,and zero at 300 yards. With a 300 Berger at 2800 fps the 338 LM, with 65 moa up, will get you to a mile or just past depending on your altitude.
I had this set up when I had the 8~32 NXS on mine.
Jeff
With a 40 MOA base, were you able to zero @ 200 yds?