Hi Bamm98,
Changes made in the deeper layers of a mattress are the least noticeable on the sleeping surface. In this instance, you would be removing half of your upper comfort layer and placing it beneath your support layer (innerspring unit). So you’d have 3" of very plush latex that would then transition to the innerspring unit beneath it, which would most likely be a transition that wouldn’t be as “gradual”, and may not allow for enough of a comfort cradle for you when on your side. The foam beneath the innerspring unit will very slightly soften up the deep support, but overall this combination would tend to feel harder than your initial arrangement. This post has a little more about how the layers of a mattress work together.
The good thing is that you have all of the materials on hand to make this particular adjustment, and you don’t have to rely upon my speculations!
Phoenix