I know you were talking about a single series and we all have misgivings about PER, but often overlooked is LeBron 1.0's 2009 playoffs, which are still by some margin the all time leader in playoff PER at 37.4 (for minimum five games, 100 minutes...LeBron had 14 games, 580 minutes), and it was similarly absurd in the first two rounds when he abused Detroit and Atlanta in sweeps, bringing in the game one loss by one point against Orlando he was at 34.7/9.3/6.9/2.0/0.9 on 65.4% TS through nine games.
His 2018 run so far currently ranks...second easily.
Third place is George Mikan in 1954, his last run before the shot clock, 19.4/13.2 at 54.3% TS and 33.6 PER. Kareem in 1977 is fourth when he averaged 34.6/17.7/4.1/1.7/3.5 over 11 games at 64.6% TS and 32.4 PER.
Jordan's 1991 is next and the only one sans Mikan to result in a title, 31.1/6.4/8.4/2.4/1.4 at 60% TS, 32.0 PER. (Though other title winning ones are farther down the list, these are actually remarkable because they were for so many games which normally would weed out the absurd ones.)
By PER, Hakeem, I believe still has the highest rated playoff series ever from 1988, he averaged 37.5/16.8/1.8/2.3/2.8 on 64% TS giving him a 39.0 PER. But it was a 1-3 loss to Dallas. And the game Houston won was Sleepy Floyd throwing up 42 points on 73% FG% next to Hakeem's 41/26/2/3/4.
