One of my most memorable shots was with a 264 WSM. In Eastern Washington in the 1980s most of the locals carried Ruger "Ranch Mini-14s" with factory loads. The coyotes learned that if they stayed at about 400 yards they were very safe. These rifles are notoriously inaccurate. I had access to 5800 acres of wheat and volcanic scabland. I spoiled the day of a pair of coyotes, male and female at a paced 430 yds. One was pointing East and the other pointing West next to each other. The 120 gr Ballistic Tip went through both with minimal hide damage. It didn't open up much. I have had similar results with the 100 gr Ballistic Tips. They don't open much on varmints. That .264 Winchester was built with a Krieger 11 inch twist barrel to shoot the lighter 100 gr and 120 gr bullets very fast with Reloader 22 and later H-1000. They fit the Pre-64 Model 70 magazine at 3.30 inches.
My latest project is a 6.5-06 Ackley, with the help of members of this forum, I have made some cases so far with a Redding 25-06 Ackley bushing die and some already case formed .280 Ackley cases from a friend. I want a longer neck to partially size and center the bullets in the chamber.
I also have a 6.5-284 Model 70 that is my most expensive custom rifle to date. It can achieve comparable velocities with the big cases with the help of VV N560. The new powders are making barrel length and not case size the limiter of velocity. Can you get 3300 fps with 130 Accubonds from your 26 inch barrel? Both my 6.5 WSMs and the .264 would have to breath hard to exceed that.
The .264 Winchester is a historical cartridge (1958). If I would build one today, I would use a 375 H&H or 300 H&H full length magazine (3.65 inches). I found the .264 Winchester a magazine limited neckless wonder.
I remember contacting Shilen once about building a custom barrel for a .264 Winchester in 1977. He said that it would be hard to get groups under an inch because of the lack of accurate bullets at that time. Fortunately the bullets have improved.
I would not discount the value of another man's 6.5 unless you have worn out a few barrels. Remember we are interest in Long Range Rifles.