The problem is you don't know what it was shot at... So how can you develop it properly? You can't you can only guess...
The massive dev chart has generally accepted times which tend to be accurate in most cases.
PRE-soak always says PE and I tend to follow his suggestions. Pre-soak 2-3 minutes.
Then follow these times... Pay attention to the exposure index and pick the one you suspect was used on the film since its already exposed.
In addition I've developed Tech Pan in ilford DD-X at 6 minutes based on EI16 with good but high contrast results. But the film was from the 1980's so who knows how that affected the speed.
Hope that was helpful and within your "request guidelines"
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