But this gives you a good idea of what "eh, fits okay" vs. "that's perfect" looks like... I give you before and after.
Before: I've taken out 2" (per side) of the 3" I put straight down the middle. Didn't need to be there. No other changes at this point. You can see how the dress is basically okay... but nothing to write home about. I'm wearing my good bra, no petticoat.
Inexplicably, the hem that I oh-so-carefully prepared and measured ended up very uneven. That's okay, it gave me a very good idea of where I'd like it to end up - it's in the perfect place as is.... so I'll be adding some length to even the longest bits. (And decreasing the volume slightly. I want a bit more sophistication for this).
Lesson learned? Vintage sewing designs are meant to be worn over vintage lingerie - including bras that position your bust in certain places and petticoats to hold your skirts out. If you want to look right, you need to wear the right underthings.
Oh, and lest you worry about the see-through factor - don't. This is an old sheet. Lined (even lightly lined) linen will be much more opaque. :)
On to the jacket!