That's about the top end for what you have... You might be able to adjust the manual trim on it get a little more.
Here are some similar posts on some other forums...
http://www.crappie.com/crappie/arkan...p-transom.html
http://www.catfish1.com/forums/showt...ng-the-transom
Good luck. I'd tie a 25ft rope with a floaty to one end and the motor to the other...just in case.