I think you are trying to take on too much. First of all, 1,000 yards is long range. 600 yards is mid-range. The rules are common, but that can be misleading when it comes to equipment.
600 and 1,000 yard benchrest are still in their childhood, at least, compared to point-blank BR. There is no overwhelmingly dominant chambering, like the 6-PPC for group, or the .30BR for score.
I'd say the first order of business is to go to a match or two. With a little planning somebody may have a spare rile you can shoot. The second order of business is to pick a gunsmith, and give them free reign on components and chambering. When you have some experience under your belt, it can be time for you to specify just what you want. If you're like most of us, that won't be where you wind up, because try 2 shows you what you want to do with try 3, but at least you'll have had a solid rifle for try 1.
Charles Ellertson
Edit: Darn it, I forgot to mention that the most comprehensive information to directly address your question would be the equipment lists for the IBS and NBRSA National Championships, and the World Open at Pennsylvania. Anybody in the top 10 or top 20 is doing it right.
But I'd still recommend going to matches and picking "only" a smith for a first rifle.