There's a post from a member (can't recall who), went down the path of a twin scroll G30-660 and it's doing over 300kW+ AND comes on about the same as a high flow RB25DET turbo.
Have your cake and eat it too in this case.
TBH, if I had a 2nd chance of building my car again (i.e. someone gave me what I wanted for my shit box, but the deal was I had to re-build another R33 and keep the change) I would just pop in a stock NEO motor (with new seals, rod bearings, ARP studs, head gasket, sump, Nitto pump), get a smaller twin scroll turbo, modify the stock low mount (keep the divider in place), and make a solid 300kW on 98RON and call it a day.