I finished putting the trim on the ribbon this morning:
I still think the trim on the neck edge looks heavy-handed, but overall I like the effect, and it looks much better than the neckline without the trim.
I have not yet got the pearls on the bodice arranged to my satisfaction, so I have followed Mary Beth’s advice and printed out several copies of a bodice photo, so I can sketch in the pearl arrangements with a pencil before trying them out on the dress. This will save me from a lot of basting!
Off to work!