Sorry, no experience with the cartridge but have used the 325 WSM on this continent and in Africa on plains game. Son and I both used the 325WSM in Africa, 200 grain Barnes or 200 grain Accubond bullets are wicked killers on elk size game. The family's biggest bull elk at 383" B&C score was felled by my wife with the 323 (325) WSM. Absolutely no reason why a larger cartridge case wouldn't be even more betterer! I'm probably telling you something you already knew and what I said didn't attempt to answer your question.
the 323 Hollis is within a couple grains of case capacity to the 8mm/338, the 8x68S or the 8mm Mazon (which is the 9.3x64 necked to 8mm). All produce sinilar velocities with with near identical loads. All approach 8mm Rem mag velocity. The Rem needs a 26 in barrel to achieve top velocity. With good bullets performance on game is very similar to the 338 Win