Spec V 09', 07, Black Mask, are all good versions of the GT-R.
The premium "Nur" version of the Skyline is excellent. Most of the late model Skylines are excellent handling cars, but sometimes slightly underpowered at lower PP levels due to their good handling.
I use the SpecV and GTAcademy versions at 600 pp, the Black Mask at 550pp and the "Nur" at 500PP.
Should be tunes all over the place for them...find Adrenaline's "Every tune that exists in GTPLanet" thread in the tuning forum, it's in third spot last time I looked. If memory serves there are well over 100 Skyline/GT-R tunes in there.