RB26det Dont do it! Unless your rich and know alot about the motor and the car u are trying to swap it in to.
S15 sr20det is almost useless unless you have cash to blow.
RB25det would be a good routr, RB20det is also a good route for the power range your looking for.
CA18det a little iron beast, can handle a shit load of power. Also can handle that kinda of power for little money compared to any other swap. Might take a little more work then the other motors but cost less then the others.
S13 SR20det nice motor, aluminum block, it revs higher then stock motor and there is plenty of potential. Will meet and exceed your power needs
S14 SR20det Pretty much same as the above motor, just with variable valve timing which im not too fond of, but thats just my preference some people like it and some people dont. Both the s13 and s14 sr20det are good motors just have to drive both and feel the difference.
KA24de Stock motor, Iron Block! its a beast lots of torque and a good amount of hp can easialy handle 300+hp on stock internals. Again, this motor will also handle your power needs. Wont cost alot of money since you already have the motor in the car, maybe just a nice rebuild. At higher rpms there can be an issue of not enough oil getting into the motor but it can be fixed not a big problem.
KA24E Sohc motor little less hp then the ka24de dohc but very good for turbo applications, it is a big lighter i believe and revs alot harder. Came in the earlier 240's i.e. 89-90 240sx. This will Also do the job.
Well there are alot of other swaps that you can do, But from what i can tell you probably dont own a 240 and looking to buy one or you just aquired one. B4 you get into swapping motors you need to learn how to drive the car and know how it runs. The stock motor will do the job, alot of people just getting into the "drift scene" think that they must swap motors to get some good hp. Im not against swapping motors i would like to swap one myself when the time is right. But there is more for you to learn b4 u start thinking about swapping and all that. If you work at a shop DIY swap is not hard there is enought information on this site and others to guide you along. If you really want to go rb series you should talk to Mckinney motorsports because you need mounts, driveshaft and other stuff to complete the swap and there quality is great.