Way to cross over from the darkside....j/k...
To answer your question, the most common JDM swap for the 240 is the ol' SR20DET drop in. The SR20DET is the motor that comes in the Silvia, the JDM version of the 240SX. The code decipherd= SR series motor, 2.0L, DOHC, EFI, turbocharged. I believe it uses the T25 turbo. Anyway, I believe the transmissions will bolt up, but you will probably need a mounting kit to allow for the extra space required for the turbo and difference in size. You'll be swapping out a KA24DE motor which is a 2.4L DOHC fuel injected motor at about 144hp. There are plenty of kits availble for this swap; it's pretty common. Search for "silvia conversion" for info. The RB motor or RB26DETT will not be able to swap into the 240 without extreme re fabbing of the engine compartment (basically not possible). It's the motor from the coveted Skyline: RB series, 2.6L, DOHC, EFI, twin t28 turbos. The Bluebird is the JDM version of a Stanza or Altima depending on the year and I think they have CA series turbo motors. A Gloria is a larger four door JDM like the maxima...proabably runs a VQ35DET nowadays, but I'm not sure. The fairlday is the JDM Z car series. They are designated with chassis codes like Z32 and Z33. The 300ZX here was equivalent to the Z32 Fairlady and had a VG30DETT motor. Now, the Z33 in Japan is cousins with the 350Z in america and they both share a VQ 3.5L motor (also used in the Infiniti G35). Your best bet is an S14 silvia SR20DET motor to drop in. $3000 should cover parts so I hear. If your interested in more in depth motor and chassis codes let me know, i have a list around here somewhere.