lots of information in that link..
you can run the engine like a 205 if you'd want using your existing 205 wiring/ecu/engine wiring/cam gears/crank gear/intake manifold.
Although the turbo dynamics with the stock ecbs is probably never going to work right. You'd need to put a single mbc on the two wastegates.
an 03 is likely an ej208 btw.
go for it