These rifles are stamped .308 Win so in theory they should not have headspace in excess of the .308 Win "field reject" dimension of 1.638. And ideally they should have headspace less than the .308 Win "no-go" dimension of 1.634.
The 7.62 NATO "field reject" headspace dimension is 1.6455, almost 8 thou greater than the .308 Win. Apart from the boogered bolt lug issues, people should expect the headspace to conform to .308 Win specs, especially seeing how these rifles were "theoretically" headspaced, proof fired and stamped for .308 Win. In most cases a .308 Win round should be OK in a smaller than "field reject" 7.62 NATO chamber. Cases will fire form to the larger chamber and there shouldn't be much incidence of case separation with good quality brass, but again we are getting back to quality, safety, and truth in advertising concerns.
There are variations in Garand bolt lengths due to manufacturing tolerances and wear, and the desired headspace in a bona-fide Tipo2 military barrel can be set by selective fitting of bolts. I like mine to run around 1.633 ( within .308 Win "no-go" specs, but a very thin coont hair less than the 7.62NATO "go" dimension of 1.6355). I've experimented with a range of .308 Win commercial ammo and 7.62 military ammo and found that a 1.633 chamber will allow the bolt to close on all of them w/o resistance.