My advice is tell him to piss off. That mod is about as useful as a chocolate teapot. The 206 GTi will give more power gain but there are problems with the ECU and wiring loom (speaking from experience). I changed out my looms and had the ECU overhauled by PugSport in conjunction with Peugeot themselves. This solved the problems with the ECU.
Don't bother with the 'standard' Gti engine, the 180 is a steel and alu setup which can handle 200bhp as standard, if you upgraded the O.E parts you can get a LOT more out of it. As Waynne said, you won't get much power increase from a non turbo'd car. If you do turbo the GTi 180 engine, whilst the actual conversion will be 'simple', unplug, plug in. The turbo will need custom mounts, custom everything to be honest. You can't get away with a bodge job, mind you if you're putting that much work into it I doubt you'd risk the car.
Its all going to depend on what your budget is, how much time you have and if you are taking it to a garage or shop or whatever, how much cash you have to throw at it. Any questions, give me a buzz.