Saw a 87 300E in a coworker's home. 265000 mile and leaking coolant. Body in decent shape. He said the water pump could have cracked somewhere because they put all new seals and hoses but it still leaks upon warm up.

Is there any life time left for a gas engine at 265000 miles? How hard is to replace the water pump? If I could not get it fix, how much I could get for if I sell it as a jank car?