I tend to rough out oversize as it's easy to remove wood with Yew as it is soft.
I'd suggest rough 'em out squarish:
For the big one:- 40mm square at the grip, thickness tapering to 20mm square at the tip. Keep the width parallel for about 2/3 of the limb then taper to 20 mm. This allows plenty for a subtle curved taper in the finished bow and plenty to adjust string line and narrow for horn nocks.
For the medium one:- 35mm square at the grip, thickness taper to 18mm. Width keep parallel for about 2/3 of the limb, then taper to 18mm.
For the 80# one:- 30mm square at the grip, thickness taper to 16mm. Width keep parallel for about 2/3 of the limb, then taper to 16mm
I'd suggest making the heavy one first and then you'll have a better idea, if it is too heavy, you can adjust the rough out figures. If it's too light it can become the 100#
Del