Standard Issue

Hello all this is my first post but my second Audi 5000 and I'm looking for a little help. I have an '87 5000 CS quattro I5 non turbo and have a few minor problems to sort out but also a major one too. The car is burning oil and producing blue smoke when starting, it also smokes at other times as well. I'm getting a compression tester to check the condition of the motor and need to decide if it's a head overhaul or something more complex and expensive. The engine runs well and starts easy it's just the smoke which lets it down. I also have another parts car with the same engine and that one is also smooth and doesn't smoke as far as I can tell. I have the option of swapping this engine but that's alot of work for me. Neither engines will set the world on fire being non turbo and both have done about the same miles, approx 140K. Any thoughts on how I should proceed would be very welcome.