If im understanding your ? correctly,then i think ,for a stiff handled bow,a 66" length,is as short as i would go,to retain the benefits of the shooting qualities of a "Longbow".A bendy handle would be 62".JMHO.Now,I agree with the string criteria,defineing the difference between a longbow and recurve,as you mention,but,by the true definition,the only true longbow,is a ELB style bow.The rest of the longer styles used commonly should more acurately be called a flatbow.Also,in my oppinion,anything shorter than 60" should be defined as a short bow.All this for the 28" draw of course.