I would highly advise using an action block and insert, rather than barrel vise jaws. There is less chance of twisting the barrel in the receiver, and having the front sight offset.
When you torque the barrel nut, first lubricate with moly grease... ordinary wheel bearing grease is fine. Torque to 30 ft-lb, back off, torque up a second time, back off. This smooths the threads and allow a truer torque reading. Now, the third time is the charm, torque to 30 (minimum is 31) then continue until the next notch lines up for the gas tube to enter the receiver. You can use a 6" piece of 1/8" dia piano rod as you do this. Stick in thru and wiggle it side to side. When it swings equal distance from side to side, the holes are lined up well enough. This is NOT rocket science.
So, whatever torque over 30 needed to get the next notch to line up is OK. It should be less than 80 ft-lbs, but rarely do I see it go over 50 lb-lbs to obtain alignment.
Also note that more torque is not better. And don't go excessive on the grease.
As far as torque on the nut of a CAR stock, Duh, clean well, apply some Locktite, and tighten by hand with a CAR stock wrench. That is not a critical thing. You can feel when it is tight, and the Locktite will keep it from backing off.
And if you got the lower together, the rest of the upper is easy.