The VMax may be a bit too fragile on hogs. Haven’t used them in the 6.8, but have in probably five other cartridges. They can be very wicked. Just a thought, maybe find a tougher bullet for hogs. Hornady SST’s have a very good reputation on hogs as well as Nosler Accubonds. I have had very good success with Barnes TSX bullets from a 6mm Remington on hogs. Also I use a 130 gr. TSX in a .308. With the Barnes you can use a lighter bullet that you typically would since they penetrate so well. They hold their weight. The TSX is a pricy bullet and you can find game bullets cheaper, but if penetration is what you want, then the TSX is a very good choice. Barnes makes a 110 gr. TSX in .27 caliber that will give a little more velocity in the 6.8 vs. heavier bullets. My 2 cents worth is use the VMax for varmints.
As to a rebarrel, I I can’t find any other suitable cartridge with the same bolt head dimensions, plus a rebarrel job could be costly. Maybe I am overlooking something. Personally I would find an accurate load for the rifle you have and call it good. Or, if you are definitely wanting another cartridge then maybe trade your rifle to something more suitable, like maybe a .243 to use mainly for coyotes, but also for hogs and deer.
