I've done two myself in my lifetime - there will NOT be a third. The problem with doing a transom is that if the boat has wood stringers you can bet that they are either gone or are going too. If you are paying someone to do it, the price will add up very quickly. While that old boat may have sentimental value, its cash value is next to nothing. If the motor is good, you may very well be better off looking for a newer hull.