15" wheels, What suspension?

On my journey of transforming the look of my mk1, I have decided on 15" wheels (correct offset), with 195/45/15 tyres.

My question is, how lowwww can i go (and still be practical)? at the moment i am on standard suspension on my 91' GTi Cabby. I want to go low and then get single headlights etc (thats the kind of look i want).

What are you guys running, and any advice?

Probably only about 40-50mm before you start having issues.