Do you have the variable pitch
prop for the engine?? The big selling point, other than the engines simplicity, was the variable pitch prop when I thought about getting one ages ago. The variable pitch propellor went a long way to making their relatively modest horsepower viable in larger boats.
What are the crack issues with the head?? Cast iron can be welded SOMETIMES. You are selling an unknown quantity till the head is fixed. Have probably had about a 50/50 success result with welding cast iron by professionals. Engine would have little value if the head is shot and a replacement can't be obtained.
A non running Saab without the variable pitch prop and a cracked head would have virtually no value. You'd have to find a another Sabb owner that had a bad block or needed the crank or rods. These weren't built in large numbers and production ceased long ago so that would be no easy task
In the engine's favor, they were tough as nails, simple, low speed/high torque engines that developed a cult following.
If I had one, would do everything I could to keep it running in my boat. But then I miss hand cranking my MD2b Volvo