I made a non-working handle short bow 43" NTN that can draw 26". It has a lot of sinew on the back though and is darn near its limits. Its weaker at 30#. If you were to take those same proportions to your desired draw length of 38" then the bow would be 63" NTN. However, I don't think you would want a bow that week so I would go longer and do a working handle. It's definitely possible to do it in the mid-high 60" range, especially if you make a composite but if you don't want to take the risk I would do 70+".