i would agree, the SR20DET would be a better choice in a 240, its made for that car, and the weight to HP ratio in the 240 with that engine is better then that of the RB26 or 25. the front to back weight ratio is MUCH better as well. that would be a tight swap, BUT i think that you would eventually want the Sr because your car will handle better and be a better alround car. IF your planing an all drag car, and nuttin else, go for it with the RB26. thats my take one that.
and i dont want an all out drag car but i do wnat to be able to pull 13's without dropping too much dough because really i wont be drifting or road racing...so i wnat a clean daily that can rip these domestics and hondas...
The RB25det can work but you would have to use a GTS-T or GTS-M (auto tranny) rear end. They are RWD but if you go this route you may need the HICAS Eliminator from stillen.
The Skyline comes with various engines
RB20DE (base engine), RB25DE (GTS),RB25DET (GTS-T or M ) RB26DETT GTR.