Regardless of group sizes or relative elevation on the targets, use charge weight testing to identify a window with minimal ES/SD. Then tune group size/shape using seating depth. Unless you carried out the initial charge weight testing at 300+ yd, minor elevation changes of the groups on the target could be a lot of things. As long as you have correctly identified the middle of an optimal charge weight window, tuning in the group size/shape with seating depth adjustment should be straightforward. Once you have done that, test a longer string (i.e. 15-20 shots) at a longer distance, such as 600 yd, to validate that the load is performing as expected; i.e. acceptable ES/SD and precision.
In the event that the ES/SD and/or the precision don't hold up for the longer string of fire at greater distance, it may be necessary to re-visit charge weight testing and follow up with additional seating depth testing to at least confirm that any subsequent changes you may find it necessary to make in charge weight haven't affected the previously identified seating depth optimum. Excessive vertical can be due to a number of different things including brass prep (i.e. neck tension as 47WillysGuy suggested), not getting the charge weight quite right, the actual seating depth used during charge weight testing being substantially off from "optimal", or even simple shooter error, among others. Until you determine what optimizing seating depth will do for the group size/shape, it's sometimes difficult to determine which of these factors may be the major cause(s) of vertical stringing. However, when you carry out a seating depth test and identify a couple successive seating depth increments where the groups tighten up nicely, then you have the answer.
Due to the number of variables that go into load development, it can sometimes be difficult to determine an exact underlying cause for some behavior observed on the target when you're at an intermediate stage of the process. Based on the velocity you're obtaining with the 200.20X out of a 30" barrel, I would guess you're pretty close to where you want to be with charge weight. With the combination of Varget, 200.20Xs, and a 30" barrel, I'd try seating depth testing next, covering a range from (at least) .003" off to .015" off in .003 increments and see what that does for you.