Hi again all,
I bought a PAL 56k GC modem for my PAL GC, plugged it straight into DreamPi and it works!
I had to register my serial and access codes with Sylverant first but once I did that it connected no problem. Levelled my character up and another player joined me too!
Really happy I can play GC PSO online now! Stream of my experience is here:https://youtu.be/mIOkJQ_VDtk