Mk5 5 engine gearbox and ECU into mk1 golf

I have been offered/given a mk5 golf with the intention to take the engine and gearbox and transplant it into my mk1 golf. Has anyone done this and if so what is needed and what problems did you have?

Thanks in advance

The engine in question is a 2.0lt tdi

I am only guessing that mk5 golfs came with more than 1 sort of engine,  if so saying which one it is may help…