If you only have a standard forend in a synth stocked R93 your limited to the .375H&H anyway (although there was talk of a run of .400H&H barrels in the standard profile).

As for long range capability, how long do you want to go? The 260g Nosler Accubond has a BC of .473 (if memory serves..) and can be spat out of the 25 3/4 inch Blaser barrel at 2700fps quite easily with ADI starting loads. Not as flat as WBY but maybe, but flat enough to take big game out to 350m with a backline hold.