Mystery Cam

It is most likely the B777 grind. It is a sol, not hyd cam. I have used a couple in 440s & they were a great street/performance cam. It was so good that I had a local cam grinder make a copy of it. 280* adv duration, 240 @ 050, 108 LSA, 0.480" valve lift.
It had 268* @ 0.020". Comp & other companies often quote their adv durations for sol cams at 0.020" tappet rise. Try finding another cam of around this duration that has just 28* of separation between 020 & 050...& had it in the 1970s. I have a bit of a smile when i hear about all these 'new' short timing cams.