Pappy--At this particuliar stage of learning I dont know if there is a rule of thumb as to which limb should be the top limb.  Just because, no real reason, I have chosen the right limb to be the top limb.  The bow is 70"'s long at this point, 35"'s to center, and each limb is 35"s from the tips.  I might also add that I dont have much artistic ability in my eyes that is why I gave up blacksmithing and stuck with just beating out knives when I want another one.  To judge the curves to make artistic work was not for me.  That is why this curvature thing is a little bit of a problem to me.  That is why I made the "tillering thingy" that is posted on another forum.  It seems to be working for me now....thanks for the advice...chuck