Yes, especially if you haven't made many bows. 66" is a good length. Page 105 in the Bowyer's Bible #1 shows typical limb widths at mid-limb to reach 50 lbs. If you looked up hickory it would give you a good place to start. With the bamboo backing you could go a bit less. I think if you ran parallel out of the handle fades at 1-3/4 inches to mid-limb then tapered to 1/2 to 3/4 inch tips you would have a good start. Tiller from there.
Good Luck!