If you want to keep the car for at least another three years you should consider getting a rebuilt engine. It is like getting a new engine for the car. Here is a link to some folks that are very well regarded in the Soob owners circles. They may not be the cheapest but they are among the best rebuilders and very customer oriented.
If you do replace the engine you might want to consider replacing the radiator also. You will have a 3 year warranty and hopefully no worries for a long time.