I think sectional density is over-rated. Far more important is momentum.
A 140gr. 6.5 mm bullet at 2700 fps has a momentum value of 54.0 lb-ft/sec
A 160gr. 7mm bullet at 2700 fps has a momentum value of 61.7 lb-ft/sec
These two bullets have almost identical sectional densities; .287 for the 6.5 and .283 for the 7mm.
OK, so then it must be the difference in the energy you say. Well, no. If you lower the velocity of the 7mm bullet so that the energy is the same, 2525fps, it still has a higher momentum value: 57.7 lb-ft/sec
The point is this: the 6.5x55 has really good killing power, especially with the 160gr bullet. Most people attribute that to high sectional density. If we say that the bullet is launched at 2500fps, then the momentum is 57.14. A .270 launching a 150gr bullet at 2800fps has a momentum of 60.0. This shows that, all thing being equal (which they never are) the .270 should penetrate as good or likely better than the 6.5 even though the sectional density is much lower.
In other words, it should kill the moose just as dead!
This is just my idea and I don't know too much about ballistics. But I started thinking about it after I talked to my friend about using heavy arrows for bow hunting. We started doing some calculations and the results are interesting. Based on these ideas I used heavy shafts and up to 160gr. broadheads with my crossbow. Penetration was very impressive. I once spined a ~150lb boar from about 40 yards. About 10" of the bolt was sticking out past the spine. May not sound like much, but that is a lot of resistance.