First, I don't want to sound harsh, but please understand I don't know you or your experience level. What are you shooting at 700-800 yards and why? Do you have a lot of long range shooting experience? In 34 years of big game hunting, I have yet to see a situation where I was faced with an 800 yard shot at a big game animal and had no opportunity to get closer.
Even if you are an accomplished long range marksman, unless you're having a custom rifle built, I can almost guarantee you your rifle won't be accurate enough to consistently place your shots in the vitals of an animal at those distances, especially when you factor in wind, weather, the unpredictable nature of wild animals, and unstable rest positions.
...especially if your rifle is chambered in 375RUM!
Given a $1K budget, and given your long range requirement, I would personally get this scope with the Rapid Z 800 reticle: