There is always the possibility that, for instance, my FH went back to be re-stemmed with a DC mouthpiece, which then throws my reading of the time into a tizzy. That would be more likely than the resurrection of the FH stamp, if I read your meaning correctly. One might suggest that the Charatan FH stamp was analogous to Dunhill's HW (hand worked) stamp, but ALL Charatans were hand made, unlike the Dunhills. So....As far as grading of the pipes, that was always going to be subjective. Ken Barnes said that they made Upshalls all week, then on Friday looked them all over and made their determinations on grade. Of course there were standards, but if they had great wood one week you might have better "P" grades than usual, and in a week of lesser wood, weaker "B" grades, for instance.
I will mention to you that there was organized, about 15 years ago, a Charatan Collector's Society. I believe that Bob Swanson and Dennis Congas were the moving forces behind this; Bob died a few years ago, and I'm not sure how active Dennis may still be (he's even older than me...must be around 80 yrs old now) but the society may still be in existence, even if only among themselves (they used to meet concurrently with the RTDA, or IPCPR show); if still in existence they might be of help to you. Maybe someone on the forum here knows.