I have a New PRRI and I would like to experiment for different overdrive/crunch sound... In december, I found small crate of NOS JAN Sylvania 5Y3WGTA from 1975 and since the 5Y3 and the GZ34 (that came stock with the PRRI) are both 2 A current rated, is it safe to just swap them ? I will rebias, don't worry, but I have limited experience with tube amps (built a 5E3, did BillM BJr mods, etc.) and I don't want to burn something... And sound wise, I hope it will be about the same clean as with the GZ34 but with less headroom and a saggy overdrive maybe ?? Don't get me wrong, I love the sound of the Princeton as is, I just want to safely experiment... Thanks ! Phil.