Depending on the condition of your existing engine and the kind of drive you want, you can get 440hpatw without opening the engine up. Just depends how much you want to thrash it, if its going on the track or what kind of response you want.
Are you looking to get everything done in WA?
There are a number of great shops around -I'll plug Elite Racing Developments any day.
I have custom intake piping (in my opinion looks better than the HKS stuff since I didn't want bling), bigger Intercooler, Fuel pump, fuel reg, good exhaust, a pair of -5's, cam gears, cams and binned AFM's - vipec ECU. My power is above 440hpatw.
If you have a much higher power figure in mind or a steep response curve in mind, then yes, stroker/the correct turbo combination, is the way to go.