Cubes is saying use a RB25DE (the block and head) but bolt on the RB20DET goodies like ECU, manifold, turbo, plenum etc...
RB25 from the R33 has VCT, R32 doesn't (IIRC).
You can get a R32 RB25DE from http://www.justjap.com/ or http://www.sssautomotive.com.au/ These are in NSW but that way you can know what price your mechanic gets it for rather than having to pay his surcharge for finding...
You could also search the forums, there's a guy with a brand new RB20 somewhere.