Here's some good rules of thumb to help calculate your bow length.
1) Bendy handle bows with circular tiller: Minimum nock to nock will be double the draw length.
2) Stiff handled bows with eliptical tiller: Minimum nock to nock will be double the draw length plus 10%. That includes a 4 inch handle and 1.5 inch fade outs/7" non bending wood.
3) Stiff handled bows with elliptical tiller (alternate technique): Minimum nock to nock will be double your draw length plus 7" for the handle section.
Remember, those are minimums. If your tillering is excellent, you will make great bows at these lengths. But if your tiller is not all but perfect, the lack of leeway will make the problems worse. A little hinge on a longer bow has less effect then one that is pushing the limits of it's capacity.
Get after it now! Post pics as you go!