Scott,In 35 years at Remington, never even HEARD of that barrel length. Couldn't be but a handful or fewer of those.
John Mann (gunsmith Remington employs for the Grand) sold a 34" during the shoot for $350. FYI...
The bore looks great, I will agree the rib looks different than most Remingtons but professional enough to be factory. I took some pics of the ends of the barrel.I would look VERY closely for a seam, joint, or evidence of modification. Its possible someone grafted a piece onto a shorter barrel to make it this length, to make a turkey shoot barrel out of. These long barrels are relatively common for turkey shoots, but don't sport the factory markings as they are grafted closer to the chamber. What does the bore look like (any visible modifications?). What does the choke mic out at?
What little is shown of the rib, it doesn't look like any factory rib I've seen (taller and a sharper angle ramp).