I've had one in 6.5 Grendel for a bit over 2 years. It's MOA with Hornady SST or AAIC 'Sabre Tip" and 'good enough' with Hornady FMJ, Federal MSR, and even WOLF steel case FMJ.
My only complaint is related to feeding issues which might not be a problem with the 7.62 which uses Mini 30 mags.
Unless you're in one of the states that require the use of 'straight wall' rounds such as the 350 Legend, I can't see ANY REASON to go that route. The 350 may(?) be the answer to a problem most of us don't have.

The 7.62x39 is an OK 200 yard deer cartridge and far better for just shooting or vermin control. Even better as you say you already have 7.62 ammo. If you choose to use the 7.62 for deer/coyote, I've found the Hornady ammo using SST bullets to be excellent.