LR Chambering Choices

Long Range Chambering Choices, 6.5X????
I am in the final planning stages of a dedicated long-range rifle project, and in order to start spending money, I need to figure out on what to chamber it in. I have decided on 6.5mm, due to the large selection of quality high B.C. match bullets available. I am planning to scope it, so this rifle will be primarily be for any/any or F-class, with some LR varminting thrown in (although I may add irons later). I have narrowed it to 6.5-06, 260 Rem, 6.5-284, or some sort of improved 6.5x55 Swede. I could be wrong, but the way I see it the pros and cons are: 6.5-284, high velocity, shorter barrel life, good quality factory brass (once Norma starts shipping) short action;---- 6.5-06, Probably the highest velocity and shortest barrel life of my options. Lots of case prep/forming. Long action only. The idea of wasting a limited barrel life fire forming cases doesn't sound appealing;--- 260 Rem, lowest velocity, and longest life of my options. No case forming, but only Remington making cases (I've used Rem cases, and have been less than impressed with their consistency). Short action, mild recoil compared to the others;---- 6.5x55 improved, Some case forming, but good quality cases to start from (Lapua or Norma) good velocity and barrel life. Problems would be possibly needing to alter the bolt face, (will 6.5x55 work with a 308 bolt face?) finding a reamer, lack of load data. Someone on the Fullbore list mentioned getting about 3000fps in a 30" barrel with a 6.5x55 based wildcat, I think it was called 6.5 Vais.--- Based on this it looks like the 6.5-284 may be the way to go, with the 6.5x55 improved in second place. Am I overlooking anything here? What barrel length and twist should I go with? I was thinking 30" 1/8 twist Krieger or Obermeyer, does this make sense? If anyone can give me some feedback on any of these choices I would appreciate it. Thanks, Tom Aiken