I did a complete overhaul of my friends Diamante 3.0, and unless your willing to drop 800-1200 like he did (still cheaper than a lesser quality rebuilt motor). I would say find a decent JY motor with good compression. I had to have the block hot tanked, honed new rings bearings etc etc. It was a worth while project but in the end, a decent JY unit might of been cheaper. Personally if compression is good, I would clean the jackets with a wire brush from a gun cleaning kit and then when back together remove the thermostat and run a quality flush treatment through it a few times.