EDIT: Looks like I was typing my response at the same time as Harvey.The Hodgdon website shows 66 gr of H1000 is max with a 160 projectile, but then lists 70 gr as the max with a 162 projectile.
It's all about bullet design and potential bearing surface on the different bullets but 4 grains is a pretty wide gap. that's like a 6% difference. I never noticed that.
In standard CYA I'm going to say, work your way up with the 160 data and if you're not seeing the classic pressure signs then maybe it's worth working up some more. A ladder load method might be beneficial with such a wide gap and potentially reduce the amount of components needed. It's not as statistically significant as other load methodologies but for hunting still an option.