I imported a widebody 155 Q4 and some other Alfas and Lancias over the years.
For cars over ten years old, there are less restrictions in terms of getting it sorted with the DVLA.
The key issue is completing a VAT declaration even if the car is EU produced and VAT is not applicable; you have 14 days to sort it otherwise the fines rack up at £5 a day until max £500 - this is not negotiable.
The export rules depend on where in EU you source the vehicle; there are several threads on pistonheads covering the same - please take care when importing a rare vehicle as DVLA are very inconsistent about paperwork and retain some of it and then ignore all the rest and register the car wrongly - ask me how I know.
there is a decent looking Q4 at superstrada in Germany but looks like skinny - any particular reason you want a widebody other than rarity? I myself prefer the skinny interior and the very early cars also have the water injection system that was not on the later cars.
re condition, rust, rust and rust, do not buy a 155 without lifting up and looking under all aspects of the boot carpeting and lining, you also need to head over to alfa 155 alfa155 knowledgebase for enthusiasts
which is also very active on facebook.
The Japanese ones tend to be looked after and have very little or not rust which is why we have seen some many Lancia Integrales brought over recently.