Remember there is no foolproof methed for accurately measuring barstock length. Each of us forges the stock slightly different and therefore must adjust for that. Also the length will differ if the foot is rounder and broader at the toe rather than hind shaped. If the heels turn in that will also add length to the measure. Fullering vs plain stamp. 3/4 fuller vs full crease. Hammer finish heels or straight heels or calks, all different measurements.
After you forge a few shoes you will become better at measuring the stock. One bit of advice is do not completely finish your heels until you are sure of your fit as this allows you the chance to forge length if you need or rasp off some extra.
Phantom