a 2.0L engine will not benefit from a twin setup.
RB25 is a good choice because its cheap, but if you want to stand out I would stay with the RB20, its a good engine. stroke it
. RB24DET would be awesome and cheap. someone local to me is building a stroked RB24 from an RB20.
In the long run though RB25 will be cheaper for sure.