I did a sort of staggered sequence of later PT's. I started at 65 to make sure I had PT's saved for future dates, then did 65, 75, 66, 76, 67, 77 etc. Then I jumped to 83 this week before the June date.
For the 70s and 80s RC, **2 Star Difficulty rating**: 70, 72, 76, 77, 80, and 83; **3 Star Difficulty**: 71, 73, 74, 75, 78, 81, and 82; **4 Star Difficulty**: 79. Hope that helps!