GT30R would be my pick for 300rwkw. It's the smallest turbo that will make the power, but will still be a little laggy on an RB25.
If you are serious about drifting, consider the HKS GTRS kit. I made 270rwkw: Head porting, Tomei cams, std manifold, std plenum. Had a great power band, great package to drive.
I have since cracked a piston, at a track day, so have upgraded to an rb30det, using the same 25 head, but with ETM manifold, GReddy plenum, and a few other upgrades. The GTRS was going to restrict the flow of the rb30 so i upgraded to a GT30R; smallest turbo recommended by a few "experts". Once the build is complete i should see about 300-330rwkw, with better response than a std high-flow on an rb25