What's the purpose of spinning it so tight? Unless you have a carb,intake manifold, cam to support those rpm's,it's pretty much useless as most cams power band starts to drop off around 6,500 rpm's.
I think it's safe to assume the bottom end was stock but the top end wasn't. There are more modified 340s around here than stock ones, pretty much everyone has an upgraded cam/carb/intake unless it's for a numbers-matching show car.
I'd suggest taking a peek over in the Racer's Forum and see how those guys are building their 340s and what oiling mods are needed for what RPMs. I think there's a sticky thread in this forum as well about oiling mods for SBMs and it was posted by a credible member who races his Mopar.
