I'm getting the impression that you want to use the same riser for the recurve and long bow limbs, is that correct?
If this is your first project, I'd advise you to decide on the Bingham (or other) designs that you want and to adhere to the material and design recommendations. That way you will have a much better chance of ending up with two very nice bows.
Experimentation is fun, but better to start off with a baseline of several successful bows.