Proportions of the original Spring Things seem (by eye) to be roughly 2/3rd Chart A to 1/3rd Charts B + C.
I have started Chart B after doing 21 repeats of Chart A.
I took the stitches off the needles and spread the shawl out (and pinned it) lightly stretched and it measures 26", so the finished size would be at least 39" neck to point. Which will be just right.
So now I need approx. 13" of border. I am guessing 5 repeats of chart B +C, odd numbers look better, don't they? So far so good. The pattern is really well written the charts are easy to read and it's all going along swimmingly.
Clickety clack, clickety clack.