Thanks for all the suggestions! After thinking it over, I decided that I agreed with Peg’s comment that “weaving something I don’t like as much as the sample” was just not in me, so I opted to sacrifice the two feet I’d already woven in hopes of getting something better. Sandra’s suggestion of using a finer weft struck me as the least invasive option, so I started with that. I wove a few test inches at lunchtime…
And it worked!! I substituted some 140/2 silk that I had bought remaindered (at the steal price of $15/lb!), and it worked beautifully. The aspect ratio is now almost exactly that of the sample. Here is a photo (click to see the larger version):

As an added bonus, using 140/2 silk as weft will make the fabric thinner, which is a good thing considering that I was worrying about it being too thick/hot. A double win!
So this is what I will be doing for the remainder of the piece. Good thing I bought about 4 lbs of 140/2 silk! That should be more than plenty. So not only do I have something to do with the 140/2 silk I was wondering what to do with, I can save some of that 60/2 silk to play with in future projects! 🙂
Back to work!
I’m glad it worked!!