You shoot what you bring. An M77 in 22 is a dream gun, way too nice for the likes of the folks out there with their plastic fantastics. That will be fun to watch.
It's the optics that really make it. You need something with either a very good reticle for holdovers, or tactical turrets that you can dial on the fly. Most have both. I prefer the reticle and rarely dial unless over 100 yards. You also need something that can focus as close as 15 yards. Most scopes can't.
Whatever is the best accuracy out of your gun that you are willing to pay for. NRL22 is at steel targets mostly, and well within the precision of CCI Standard that I use. Many are using SK Standard or the expensive SK and Lapua stuff even.