I ripped it last night. Right up to the arm holes.
I took out one of my favorite sweaters last night after posting - the one that has the best fit - and measured the diameter. Then I measured the purple sweater. 4.5 inch difference. No wonder I didn't like the way it fit! So I made like a frog a ripped it.
Got my gauge. Now all I need to do the math to figure out how many stitches I need to put on before continuing the main body. Unfortunately, that involves math - something I'm not the best at even on a good day, let alone after a long day at work. Should get interesting...keep you posted!