The 602 is probably the most reliable Mercedes engine built next to the 617. It does not suffer from the warping heads or glowplug issues that it’s six cylinder siblings do. It will be more tuneable than the N/A diesels. Finally it will be the right and easiest fit for your car. Anything else would be an exercise in wasting time. One could argue that the better option would be to find another car since the engine is the most valuable part by far. That is unless the body is in extremely good condition.