Which size should I cut for my Maritime top

I'm going to start my first maritime top, and I'm not sure about the size I should cut. My bust measurement (36'') points to an 8, but I was considering the possibility of enlenghten it a couple of inches to make it reach my hips, that are not an 8, but a 10 or 11...(40 1/2''). I have never mixed two sizes in a pattern. How should I do it? Where should I begin to move to the 10 size line? Or should I cut directly a 10? I'm afraid that it results too dropped at the shoulders. Thanks in advance for your help!