Looks a pretty clean engine anyway. Especially for a diesel just looking at it from the top.
Thing is with engine life its hard to test unless you start stripping it anyway and looking at its wear. In which case once you are there you'd be silly not to repair it.
You are better off just using it. The engines are strong and turbo's seem to last for around 100k.
There is no more gamble on a car fitted with a new engine than there would be in buying a second hand car.
The risks are the same.
How many people go to view a car and start opening up the sump to check for tolerances on the shells?
Checking clutch pad thickness. Valve clearances etc?
Alfa 166 2.0 Twinnie - LPG and a few trick performance parts