With the off-the-shelf choices currently available, I don't believe either of the mentioned wildcats are the way to go. If you want that level of case capacity in a 6.5, the 26 Nosler would be a better and easier choice. However, the tradeoff for going that route involves more than barrel life. I am seeing reports of shootability issues as case capacity increases, such as a tendency toward pressure spikes in the 26 Nosler.
I own a .264 Win Mag. Even though it has less case capacity than the cartridges you are considering (and the 26 Nosler), it is still a VERY overbore cartridge that does its best work with some of the slowest powders in existence. Based on my experience with it, I don't find the idea of even more case capacity to be very appealing. I am very fond of my .264, but I feel it is right at the practical capacity limit for the 6.5 bore size.
If more speed than the 3150-3200, that is typical of the .264 with 140 class bullets, is desired, lighter monometal bullets (and/or longer barrels) may be a better answer than more case capacity. For example, I would expect it to be possible to safely push a Cutting Edge 130 MTH (with a 550 G1 bc) to 3450ish from a 26" barrel with a .264 Win Mag class cartridge.
I would expect cartridges like the 6.5 SAUM and 6.5 SS (Sherman Short) to be able to deliver similar performance.