It may not be GTR, nor a RB26, but you mentioned a nissan 3 litre,
Jun's Z32 demo car - VG30DETT ran 419.84 km/h in 1991 - record still stands today
http://www.junauto.co.jp/democar/jb-z32/index.html?en
2001, Jun attempted to beat the record with a supra (Akira supra)
aerodynamics play a huge part when you move into higher speed regions