it's doable and been done, seen it done with a G60 unit and various eatons.
the 1.8 NA 20v isn't worth converting to take boost because you can buy a 1.8T for less money and fit that, so then your buildng what you can buy and thats not good.
so you buy a 1.8T and while sat there unbolting the turbo you should aks this question, why am i unbolting a turbo to spend a load of cash fitting a ( in the g60 case ) an old supercharger that less reliable and will problay need an expensive rebuild just to make less power than it would have done with the turbo.
or in the eaton case you can if you can be arsed to make all the brackets fit a really big one and make lots of power and torques but eatons are very good at killing engines and gearboxes, they puff harder at the lower revs so you can drive on the torque in high gears at low speeds and it'll pull but that gives the motor and transmition a hideing
