75 to 80 pound feet is what I use.
That is an arbitrary figure. Keep in mind, in order for a properly installed threaded joint to function properly, it must be placed in tension. I am skeptical that 35 to 40 pound feet of torque places a 1.062 or larger thread in proper tension. The important thing is to insure that the barrel thread actually advances upon one another.
Several things come in to play. The two most obvious are the finish and quality of the threads and the type of lubricant used.
I use Jet Lube, simply because my shop buys it by the case. We use it to coat shafts when we are shrinking large liners on to the shaft.
https://www.grainger.com/product/30...kwcid=AL!2966!3!281698275537!!!g!472123448796!
To insure that your barrel does advance, I bump it up firmly, then with a sharpie pen, put a line connecting the barrel shank to the action. Then tighten until the marks are about 3/32 apart. That is about 80 pound feet.
Years ago, some well known shooters told others that on a Benchrest Rifle, all you had to do was snap it tight by hand. Shooters that believe that have no understanding of how a threaded joint performs in application.