You are starting to find out why a free boat is the most expensive one. Seldèn could probably provide you a new mast, but it would likely cost quite a bit. Do you have the sails? Looking for used spars online may unearth something, or it may not. The quickest solution might be to find a rigger nearby who could perhaps re-rig an existing mast to fit your sails. He may know that a Catalina 22 or some other mast could be cut down to the right size for you, for example. Paying for his knowledge might be well worthwhile.