My sons Alpha 40 needed 3/4 oz weight in the nose to ballance. If yours needs weight in the nose I would just remove the blind nuts, double up the plywood with some good epoxy, add tri stock as mentioned and install new blind nuts. If it is not tail heavy I would remove the old wood and install new. The firewall on that plane is notched into the fuselage for strength so you will have to epoxy tri stock in with the new wood to strengthen it. Here is a thread of the repairs on my son's Alpha 40.
http://www.rcuniverse.com/forum/m_11...m.htm#11237977