Can I safely shoot surplus 7.62X39mm ammo in a Mini-14 with a .308" bore? Surplus ammo is not known for it's accuracy, but will the larger bullets make it any worse?

Yes and no, respectively.

Yeah, they shot just fine in the Mini 30 I had. As far as accuracy went, well, it was piss poor.

Elk, slug that bore before you assume it is .308. Early Mini 30s did use that size, but Ruger went to .310 many years ago. I'd be willing to shoot the mil surp ammo in either case, but it's nice to know.

It's also something you must know if you feel like loading up some good ammo for it. That steel case stuff is incredibly bad.

Sure you can, I did it, but accuracy? What accuracy? Only accuracy I have seen with this cartridge has been with a customized Mini-Mauser, and believe it or not, the MAK-90.