Sizing question

So I measured Ms. 6.5. Her chest is 22.5 inches, which is a size 2. The length she needs is 27 inches. That's about a size 7. Generally I am making size 7 dresses for her (eg- the hopscotch). I can't see cutting a size 2 width and a size 7 length! Got advice? (other than make a muslin... I am lazy today and need a quick fix for finding my mojo!1)