craftgrrl | Taking in at the waist

I have a few of the Francis Grimble books with the historical patterns in them, and have figured out how to successfully scale them up with the rulers. Because they are made for the silhouette of the time, most of them have far too great a bust to waist / hip to waist ratio. Now, because of the way they are drafted and the way the rulers work, it's impossible to figure out what the differences in sizing are exactly, without drafting a number of sizes and measuring the pattern as best you can. They go by bust size, and no other info is given. The alternative is letting out the waists manually in the drafting stage. I'm looking for advice on how best to do this when the difference is significant. Most would have to come out 5-6".

So you can see what I am talking about, behind the cut is a pic of a bodice drafted to 40" bust.

I'm really hoping to find a way to use these patterns, they are so fabulous! I'm starting to think that starting with a fitting waist letting out in the bust would be easier and would allow for keeping some of the lines more actually, but like I said, it's impossible to work out the waist measurements without actually drawing up the pattern.