Well If it were me with the choice, I'd pick the Carly.
However, my decision (bottom line) would be whether the parts of the car that would be easily sold, were in good enough condition to recoup my £600. If so then I would consider it well worth the (now measured), risk. Its unlikely to be a nightmare anyway but with this 'insurance', you've covered yourself in the event of worst case scenario.
As far as I can tell from your post, the £600 is easily recoverable so I would jump at it. The distance is a one-off issue. The risk of the reliability of a car (Lancia) that I know little about, is potentially an ongoing issue so I wouldnt consider distance a problem - unless you can't get there of course; in which case, you probably wouldn't be considering the carly at all.
hth