You will need the RB25 power steering bracket (the one that goes to the block). The Rb20 one will not work. You will also need to replace pulley with RB20 one.
Once you do that follow the guide.
https://www.nicoclub.com/archives/ho...p-on-rb25.html
Edit: To be honest I recommended installing a RB25 harmonic balancer and just buying rb25 powersteering pump and bracket. They make brand new rb25 pumps (I just bought one) and other stuff as well new such as the harmonic balancer. Not so much for 20. Sucks, as all that is more money but it pays off in the long run in my opinion.