u/MelocemBYSL

My current car is Audi A3 from 2015 with a 1.6TDI engine. I came across a high mileage BMW 316d (260.000 km) for a good price. I was thinking about buying it and changing the engine, but I don't know much about cars so I don't know what to change exactly. Do I change only the engine or other parts as well? I live in Belgium, and the car itself is 5500 euros. Let's say the new engine will cost 3500-4000 euro it's 8000-9000 euro total. I also have to pay for labor, I don't know how much it costs. Is it worth it? I also want to put in a 320d engine for better performance, is it possible?