Far more typically a hybrid conversion having an RB30E block along with a twin cam RB25 head without having a turbo can be used as being a foundation for your RB30DE.The RB25DE cylinder head through the A31 Cefiro C33 Laurel or R32 Skyline (aka: Non VCT) can be used. The RB25DET (within the R33 Skyline or C34 Laurel or Stagea) head can also be used