I've driven PA 449 and NY 248A/NY 248...both are roads marked mainly 55 and were good roads for the Twin Tiers...shoulders exist but minimal, curves aren't too bad with an exception here and there. Same with PA 872. There isn't difference with the 2-lane roads in the NY Southern Tier vs the PA Northern Tier. Some of the PA routes can be hit or miss.
PA 879 is near Elk country, if you'd be interested in that.
Near the intersection of PA 49 and PA 449 is a rare Triple Divide...where the Allegheny River head is which flows SW towards the Ohio, the Pine Creek head is which flows SE towards the Susquehanna River, and the Genesee River head. There are a few markers nearby.
Evening/dusk...not too bad but watch out for deer...that's the main concern in any of those areas.
US 219 is a slightly higher quality 2-lane road...but I'd say the differences are minor. US 219 has more trucks, wider shoulders, truck climbing lanes, and softer curves...but still curves. IF you choose to take US 219 and still in daylight, check out Kinzua Bridge, which isn't too far off US 6 near there.