From the photos and the sellers comments, it has a N1 RB26 replacement engine (R34 GTR V-Spec II Nur) But you'd want to see it in person to confirm.
They used them in the N1 GTR's / R34 GTR V-Spec II Nur and M-Spec Nur.
N1 RB26 = Race Spec engine from the Nissan factory.
That engine alone with no turbos was going for $15,000 at Just Jap: http://justjap.com/genuine-nissan-skyline-r34-gtr-nur-engine-rb26dett.html
Along with all the decent mods listed, I'd say it's ok...
But I'd find out what turbo's the car is running.