You could do a little test for specific gravity and relative tension/compression strength as I did in this thread (broken link, remove space in www part):
http://ww w.primitivearcher.com/smf/index.php/topic,68656.msg963505.html#msg963505
I believe Tim Baker wrote about 'rule of thumb' bow dimensions, based on this test in TTB 4 (or 3?)
Good luck!
/Nicolas