It's one of those ... You deal with it because its such a great film.. Things IMHO
Also, why not just look at the times between HP5+ and FP4+ and half that time and subtract it from the FP4+ they are similar-ish films from the same company so the dev times should be a lot that much less of a stop from FP4+ to PanF+
It's a good starting point at least.
Good luck! I love it in Ilfsol 3 and Rodinal 1+50
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk