As it turns out, once I counted stitches and rows I realized I had shaped the front piece exactly the same as the back. I think the difference in the way they looked comes partly from the bust shaping, and partly from the greater weight-per-stitch of the hem on the narrower front piece. Blocking helped a lot. So I knitted up the right front. (Actually, first I knitted up a second left front, but with buttonholes. Then I ripped that out and knitted the right right front.)
I whipped up a sleeve to see if there was enough yarn to make the whole sweater one color (there is) and to test my ability to draft a set-in sleeve on the first try (not there yet). The armhole is deeper than I intended -- it turns out my gauge is just slightly different from what I expected -- and I am not willing to reknit the sweater to make it higher. Although I don't know why not, really. Will have to sleep on this.
Anyways, I basted the whole thing together today, and realized that the sleeve is too big. So I pinched out the amount that seemed appropriate and rebasted. What do you think? (Funny pucker in the middle of the back is just wonky basting. Peculiar expression on my face is nearsighted attempts to aim camera. Wallpaper is unspeakable.)
It's still pretty big, but the whole sweater is roomy, and I think if I tighten the arm up any more it would look peculiar. Other than the low armhole and a bit of residual hem flip, I think it looks pretty good. Or should I rip out all three body pieces and redo them with a higher armhole? I don't think this sweater deserves that much fuss, really; if I just finish it off the way it is I'll have a nice, warm, well-enough fitting sweater. And given the fact that fall has finally arrived in Oklahoma, I'm eager to have this done and ready to wear.