No 1.8t came with forged rods or pistons... what you have heard is incorrect.
The majority of internal water pump 1.8t have forged crankshaft if that's what you mean...
A lot of misinformed things have been mentioned but the important thing is if an engine conversion is to be done it is best to start with the throttle body - is your car drive by wire or cable? But is out of the scope of this thread.
I agree with the sentiments of other members; it's cheaper and much less headache to just buy a 1.8t gti and stick a few bolt on mods then map it as opposed to paying someone to source and do the engine conversion on your behalf.