I owned a 6.5-06 ackley improved and LOVED it. However the time and energy required to make up 500 brass, fire form them, anneal them, load them..... It was a lot of work and a labor of love. Low recoil and very looooonnnnngggg sexy low drag bullets that fly real flat... Loved that.
If factory ammo availability was never an issue and I knew the airline, kids or wife couldn't misplace my gorgeous reloads..... Then I would Build and handload a 7mm built on the 338 lapua case. Slippery long heavy bullets at less weight than 30 cal equivalents and push them through a 30" barrel would allow you to run heavy loads of rl25, retumbo maybe h1000.
For factory ammo in a short action the 7wsm seems to be VERY impressive cut the barrel with "freebore" to allow loading the bullets with long lead lengths to max magazine length, 26" barrel to take advantage... Might make a good winter project.
BTW that 180 accubond is a favorite of some long range elk hunters I know... They guarantee it expands nicely to 1600fps. Regardless if fired from a 308 or a 300ultra... I will let you figure out how far out they are hitting them!