Yup, it's already been said, you don't often see a stave that long.
It would be criminal to saw 1/3 of it off.
Another reason is an ELB is slim so you may even get 2 out of it. One from each end overlapping in the middle. Don't risk spoiling it by being greedy, but if you lay out your first ELB carefully you may get a second or a kids bow out of the waste.
(I allow about 30mm x 30 mm at the grip and 20x20 at the tips when roughing out, but that's cutting outside the line)
OK. maybe make the one on the right bigger and the one on the left a kids bow... but it depends how big your hands are
Del