Engine Replacement on A 2001 Subaru Legacy Station Wagonwith 100,00 miles

My timing belt malfunctioned and appears to have damaged the engine valves in the process.  I am being advised to replace the engine with a used 54,000 mile replacement engine.  Should I pay 2700 to fix it or scrap the car and replace it?  Is it worth investing in a replacement engine f I want to keep the car foe another 3 years while y son finishes college and then sell it?  Will it be worth the investment in terms of resale value?  I am the original owner of the car.  I do not drive it very much as we live in the city and work within a few miles of where we live.