Maybe I'm a bit thick but I don't see the point in your post. I don't think a 158 grain is too heavy for the 7-08. I have shot 168's in the 7-08 and 175's in the 7x57.
The point is that the cartridge is designed to be at its best with 140 grain bullets. Same as 308 was designed to be at its best with 144 grain bullets.
That you can load heavier isn't being questioned. You can load a 200 grain bullet in a 38 S & W revolver - we British did and called it the 380 Mk I. But velocity was abysmal at much over short distances and trajectory like a rainbow as simply there was not enough room for enough powder for a decent initial "oomph" or to do it at anything less than borderline maximum loads.
The same with 160 grain and 175 grain bullets in the 7-08. There is not enough room for enough initial "oomph" AND you are using maximum loads to even get much above 2400fps with the 175 grain. Indeed some of those loads in shorter barrel rifles will not be "deer legal" in Scotland in velocity terms. They struggle to even approach the velocities of the old 303 Mk 7 in a No4 or SMLE with the same bullet weight.
Now good as it was the 303 fell out of favour as a stalking round not just because it wasn't chambered in fashionable rifles but because at longer unknown distances bullet placement became imprecise as the trajectory curve was so steep compared to rifles with a muzzle velocity of 2,700 and above.
You can't get 2,700 and above in a 7mm-08 with any 175 grain bullet weight load that I would consider safe or sensible.
And with the 160 grain again you will struggle to get above 2,600 fps in a 7-08 with a barrel under two feet. The case capacity just is not there unlike in a 280 or 7 x 57.
The reloading manuals may say XXX but the chronograph doesn't support it always.
I think that if Mr Mick the Brick wants to use nominal 160 grain bullets or heavier in his 7-08 he will be disappointed in its performance. Especially if it has a short barrel much less than two feet.
Using anything a 175 grain bullet (or a nominal 160 grain) in a 7-08 is not much more than duplicating (at near maximum load pressure) standard load pressure 303 performance!
Wonder what the trajectory will be like with a 175 grain in the 7-08? Think probably as bad as the old 303 Mk 5 "Jungle Carbine"!