Pick the one that you like/are most comfortable behind and or shoots the best...extend your range to the distance you plan to shoot and shoot a 20 shot group then check your target..if you can keep all 20 in the 9 ring or better your doing good and most likely need to practice more on position and trigger control... if your 20 shots are all over the target then you and your load need work...by yourself some 600yd F-class targets and practice in the wind and learning to read the wind.
And you might want to start saving now for a new barrel for spring when you start your matches...or have the barrel your going to shoot set back at about 2000 rounds. Theres a lot more to this than what we have talked about like when to clean your barrel? Does it shoot better fouled or clean? How is your load going to preform with atmospheric changes?

If the guy you bought the rifles from is local id pick his brain for all the info you can get and try to go to a match and talk to the guys and girls there.