1,000 yards, generous budget, 10 shot strings, 50 rounds per match.You have to be more specific. How many yards? How many Shots per outing? Unlimited budget? There are many new Brass configurations out there. New usually means more expensive.
If it was going to be fired rapid fire as it usually is in 1000yd BR, then I would likely opt for a 284 Win.1,000 yards, generous budget, 10 shot strings, 50 rounds per match.