Getting the perfect fit using Lutterloh Pattern System isn't as difficult as it can seem.
Lutterloh recommends testing your size by creating their basic vest pattern. I recommend trying out one of the few sloper/basic dress patterns they have in the 1949 book and the other in the 1954. These patterns are not only useful for fitting the neck, bust and waist but also are useful for creating your own designs.
I think of a sloper as a flat dress form, cut into front and back pieces. Lay your pattern on your "flat form," and you can see immediately whether the pattern will fit you because you can see how and where it fits the sloper, and where it doesn't. You'll almost certainly have to redistribute the sloper's dart shaping to line up with the pattern's.
The flat-pattern method begins with the creation of a sloper or block, a basic pattern for a fitted, jewel-neck bodice and narrow skirt, made to the wearer's measurements. The sloper is usually made of lightweight cardboard or tagboard, without seam allowances or style details. Once the shape of the sloper has been refined by making a series of mock-up garments called toiles (UK) or muslins (US), the final sloper can be used in turn to create patterns for many styles of garments with varying necklines, sleeves, dart placements, and so on.