Realistically I don't think you will get 200bhp from an 8v without turbo or supercharger and other work.
From a 16v you will need headwork, cams, matchporting inlet and exhaust manifolds, individual throttle bodies, stand alone management, remap etc. Cost you about 2 to 3k to do it properly. £300 porting, £300 cams, ITB's £600, management and associated bits £1000, remap £250 all approx.
As Wayne says cheaper and easier to go for a 1.8 turbo lump and have it remapped.
Paul
The 16v will be more efficient and reliable and 200bhp is easily achievable.
The 1.8t will have to run at a higher boost and that can blow turbos! And its not just a remap!
So easily achievable and cheap then. 
It will take you 2 to £3k to break the 200bhp barrier on a 16v, but you can get very close to 200bhp for a lot less money.
Headwork and manifold porting £300, inlet cam £150, remap £250, and a few other little bits. So for under a £1000 you could get to nearly 200bhp on a valver.
To swap to a turbo engine will cost you the price of the engine and ancilliaries, plus extra for the parts for the conversion, and you will have the added bonus of having to replace your turbo in the future, sooner rather than later if you have it remapped.
Engine swops make no sense, tuning an 8v, 16v, or VR6 makes no sense, go and buy a car thats got what you want straight from the factory, save the money and hassle. If we all thought like this we would all be driving around in the same car and the world would be a boring place.
Modifying, tuning, engine swops, customising are all what makes the car scene more interesting, if no-one did it the magazines and shows would be very boring - looking at and reading about standard cars as they came out of the factory.
Some people are polishers (not my cup of tea), some people want the best mechanically, some are just happy to drive the car as it is, each to their own, neither of the first two ways make financial sense. Owning a car can become a passion and getting rid of that car can become hard to do, thats why people spend more money on converting that car either cosmetically or mechanically.
Just my take on things
Paul
PS Len you drive the right car engine wise but lose those blue lights.