I've had 81 points before, and I have a guy right now in Crum who started as a 17 in PER and is now at 71 and still high (he's a junior), so he has a shot of hitting 80. But I've never had that kind of improvement in two stats. My best is probably a guy who improved 80 in PER, 35 in SPD and 35 in passing.
I have had a guy who improved 35+ in five ratings in D3, but not so much in any one individually. 41 in SPD (19 to 60), 41 in REB (34 to 75), 37 in DEF (36 to 73), 49 in PER (13 to 62), and 49 in ST (48 to 97). Was definitely one of the best D3 PFs I've ever had.