I have an R33 RB25 on the engine stand right now. It's almost ready to go into my 280Z. To answer your question, I have a 7-blade HX35 and it does not clear as a direct bolt-on. For the oil feed, the factory line fits, but the stock RB oil feed banjo bolt on the stock turbo is 12mm x 1.25 while the Holset requires a 12mm x 1.50. The oil drain line fits up as per factory. For the eliminated coolant lines, a 14mm x 1.50 oil drain bolt will plug the banjo hole off on the block.
I have seen people find an appropriate banjo bolt from another application and made it work. I have also heard people take a standard bolt and drill it to banjo specifications. Note that the stock banjo bolt acts as a restrictor. I don't think the Holset really needs a restrictor to avoid issues, however.
The only issue is that the turbo fouls the exhaust manifold at the compressor cover. If you clock the compressor output straight towards the block (in other words, a useless clock position) it will clear since the radial diameter changes, etc. With the compressor outlet pointed down, it will not clear. I suspect you merely need another T3 flange to be used as a spacer when you mount the turbo to get it to clear, but I have not tried this yet. Note that, as others stated, the turbo and the stock exhaust manifold are both twin scroll. I have not found a twin scroll "u-weld" flange to space it out. Likewise, you will need longer studs for the exhaust manifold.
Note that the exhaust manifold studs are dual thread. They are 10mm x 1.25 on the turbo side and 10mm x ??? on the manifold side. It's a coarser thread spec, but I have not measured it yet. The holes in the exhaust manifold for the studs are obviously blind, so you could just get some high grade threaded rod and cut them to length, etc.
Please note that I have NOT tested fitment with the factory engine mounts, as I am doing a swap into another chassis and did not use the original mounts. I have them however, so I can test it out if anyone is interested.
As a side note, another nice thing about Holsets is that the compressor wheel is balanced individually (on the '35' sizes, and some others) and the turbine wheel and shaft assembly is balanced individually. This means you can rebuild it without indexing or having it rebalanced. Just pull it apart, stick the new bearings in, and slap it back together.