Unfortunately it doesn't work that way.

When you are talking about high velocity rifles and various weighted bullets, the rate of twist in your barrel will determine how heavy of a bullet your gun will "stabilize". For instance, if you have a slow rate of twist in your barrell (i.e. 1 in 14 or slower), your gun will shoot lighter bullets much more accurately than it will heavier bullets. If you have a fast rate of twist (i.e. 1 in 8) it will stabilize heavier bullets much more effectively.

With the 2 bullets you discribedbeing so far apart in weight, more than likely your gun will not shoot both bullets well, much less have the same POI.

I've seen guns shoot heavier bullets with a POI that is higher than a lighter bullet. I don't know that I have an explanation for that but I have seen it.