When talking about precision shooting, which 1,000 yard shooting is, I never want my scope at either end of its adjustment range even if it works. I want my scope somewhere in the midrange.
I do not have my ballistic calculator in front of me, but my 6.5x47 Lapua, that I shoot 1,000 yard with, took 32 MOA from 100 yard sight in to get to 1,000 yards. I would estimate that with 175 grain .308 rounds, you might need a little more. I think my Palma rifle, though I shoot 155s and 165s through it, needed more like 37.
My suggestion to you would be, put a 20 MOA rail or bases on your rifle, Than you can adjust up and down within reason. A 30 MOA rail would probably be better for 1,000 yards, though you might not want to be taking it on and off all the time as you change shooting distances. For, me even better is to do the 20 MOA rail and then use Burris Signature Zee rings with inserts. With the inserts, you can add or subtract MOA easily (You can convert MRAD to MOA and visa-versa easily enough) so it is easy to make the switch from one day shooting 1,000 and the next day 100. Also an added feature is that the inserts will protect your scope and eliminate ring marks.
At a 1,000 yards, with your 25x scope, it does not take much misalignment to be way off. I am not a hold over or hold under fan for that reason.
There are plenty of Ballistic Calculators at the Apple Store for you if you have an iPhone and there are others for other phones and tablets. If you know the particulars, they work great. Also, if you really want to shoot at 1,000 yards, I would highly recommend you start hand loading.
Where are you located? What 1,000 yard range(s) do you plan on shooting at? I shoot at two in Pennsylvania.