I would start from the ground up. rebuild the engine and get it to peak condition. port match the manifolds (intake>Head/Head>Exh/Exh>Turbo) and make the ports as good as they can be (smooth with no lumps or bumps).
decide on the size of turbocharger you need to flow the air you need for that torque output, big intercooler, probably larger injectors at a slightly higher pressure. I think the std 150ps spec injectors flow enough for 200/220ps at most..then you start running out of time to squirt enough fuel in..
They're are racing engines based this engine that make somewhere around 280/300hp
1.9 JTD M-Jet 16v 140ps.
Gas flowed head, Polished valves, Port matched manifolds, New Turbo.
JS-T primary Decat, MrZ full-bore Center Decat , Oil recirc tank, Big filter conversion.