I have never heard of a 180 grain load in the 7mm-08. I know the 7 mag family of cartridges normally shoot that heavy of a bullet in a 1:9 inch twist. I would recommend a 1:9 to 1:10 twist for the 7mm-08. I would say that the 7mm-08 is a solid 750 yard performer with the proper equipment and PRACTICE! a 140 grain remington accutip boat tail is leaving the barrel at 2,860 FPS with 2600lbs of Kenetic energy. At 500 yards you will have a drop of 50 inches with a velocity of 1,987 FPS and 1227lbs of KE which is plenty for deer sized game. With reloading I am sure you will be able to develop your load to suit your needs. It will have a ballistic coefficient roughly in the .450's. What is your goal with the rifle? Targets, Large Game, Varmints, ELR rock busting?
For rifles why is 2,000 your limit? Do you want a semi custom rifle
? I would look at the remington model 7, remington model 700, cooper, savage, weatherby, and tikka. All of those minus the cooper will be under 1,000 depending on model. You can always build a 7mm-08 off of a remington action but that might push your 2,000 dollar budget. Savage might be a better option since its cheaper, just as accurate, and you can do most of the gunsmithing yourself. For barrel length, a 24 inch heavy barrel will do you fine.
Also, there is a gentleman on here who is using his .308 winchester for extreme long range shooting (I think he has it shooting to 1,200 yards accurately right now). He will have useful info on pushing the limits of cartridges.