If that motor is in running condition, I feel he would find a lot of interest up to $175.00 from those looking for one. If it has been sitting for the last 50 years, it will need at least coils, carb kit, and impeller, which depending on the quality of parts, will be over $100.00. Because of the condition of the motor, I feel I wouldn’t have any problem getting $125.00, not running, at a club swap meet. It’s not hard to get more in these than they are worth. For most it’s a hobby, like golf. You may have to pay a little to play from time to time. The factory oil recommendation can be found under the choke knob. 1/3 of a pint would be 24 to one, not 16 to 1. I have 59 & a 61. I’ve had the 61 -19 years. I’ve had the 59 – 55 years. Because of the improvements in oil, I run 3 oz of oil per gallon (42 to 1) in them without any trouble. Video link below. Not a recommendation. My experience for you to use to decide how much oil you would be comfortable with. Video Link – https://youtu.be/r1vVMls8OU4?si=255PdIjuKDI9-_vj
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.