For the peice of mind go for a hybrid, ive got a k04 on mine and it is not as straight forward as people make it out to be. i would recommend ie rods as i bent two on my old block.
The following will need modifying:
Heater matrix pipe beneath the coldside turbo housing.
Oil return line needs extending.
Coolant line off after run pump needs extending (I got a full braided line made up irrc it cost £10 to do so)
Coolant line off the back of the block needs extending (Custom braided line made up / Otherwise use K04 coolant line for this)
Oil line off oil filter housing can be bent slightly to fit straight onto the turbo (If using the standard k03 line)
Standard
Ibiza fuel pump will be fine on 3bar as Bill will tell you as long as its still in good working order.
Q peng downpipe is a straight fit but only at 2.5" as 3 inch is not available unless you have it custom made.
standard
Ibiza MAF element in 3" housing.
S3 Injectors
S3 manifold
Gaskets to suit
k04 TIP
Mapping to suit
That should sum everything up.