You're kinda boned.
TL;DR from his post...
30mm tube, so only 40MOA adjustment range.
Last time I was out my 16in was launching 168s and looking at ~45-47MOA drop. 20" barrel and 175s will cut that down a bit, probably to around 40.
Being that scope is not FFP, your options are even more limited.
IMO, it's not worth dropping $250 on a mount for that optic. Your current setup, if you truly have 22moa elevation left, should be able to take you close to 750y. If your scope has MIL/MOA holdovers, at max magnification, you should be able to figure out a small holdover for 750 0-2MOA if necessary. At 1000y it's going to be basically double that, i.e., my MIL holdover at 750 is 7.8 and 1000y is 13.7-14.1 depending.
It's simply not an adequate scope pairing for 308 at 1000y. Shoot out to 750 as-is and move to a 34mm FFP optic with a generous adjustment range.
ETA: with a 20MOA mount (0 MOA rail), my 34mm scope has ~20mils / 75moa elevation travel remaining