7/16 studs will handle up to around 80 without any trouble. That's the spec for the later Chevy 4x4 with that size studs. However, I would go closer to what the shop manual says, no more than 75. Make sure to request that the do not hammer the nuts on with an impact. Running them up is OK, with maybe just a tick past seating the nut, then hand torque them to final spec, going around the pattern at least 3 times.
If you have your own torque wrench, recheck the nuts after you put about 25 miles or so on them. You would be surprized at how loose thay can get once the weels seat in to the hub.
