The Arista film is definitely not HP5. Actually, my tests have shown that it is not even close. This film is about twice as grainy as HP5 with about half the resolution. I tested several rolls of 120 in studio lighting. I processed it in PMK. (I think development was 13 minutes).I matched Dmax,Dmin to HP5 shot and processed under the same lighting conditions. The difference was considerable. Next to the HP5, the film pretty much fell apart. I found it to be unusable for my taste. Not even able to enlarge it to 11x14 without significant grain, lower contrast, and resolution.
I have heard several people refer to this film as repackaged HP5. I wish it were true, but it is a myth. Its characteristics are nowhere near that of HP5
Sorry, just had to get that straight. However, to your original question.: Although, I did not test any LF film, I found that the Arista 120 in PMK needed the same development time as the HP5. I tray process HP5 for 13 minutes. Theoretically, the Pyrocat should be about 70% of that or 9 minutes. I would start there.
D