Long overcame some early jitters on Saturday to secure a 21-19 21-9 victory over India's Kidambi Srikanth and set up a showdown against Hans-Kristian Vittinghus, who claimed the bragging rights in his all-Danish semi-final Jan O Jorgensen at the season-ending tournament.
Sung Ji-hyun and Tai will battle it out for glory in the women's final on Sunday, although only after the latter launching a spirited fightback to beat Saina Nehwal 11-21 21-13 21-9.
World number two Long trailed for much of the first game against Srikanth before eventually levelling at 18-18, rattling off six points in a row to take a 1-0 lead.
It was a very different story in the second game as Chen dominated thanks to seven-point streak that edged him 12-3 ahead, a platform that allowed the 2012 SuperSeries Finals winner to progress to the final, where he was joined later in the day by Vittinghus.
Seventh seed Vittinghus got the better of fellow countryman Jorgensen 21-11 21-17 to reach the final for the first time, having been a losing semi-finalist in 2012.
In the women's event, there looked to be only one winner when Nehwal went 4-0 up in the second game against Tai after comfortably securing the opener.
But Tai finally found some form to blow her opponent away, even though she was not that surprised by the turnaround.
"I would regard my form today as normal. Maybe I can give myself eight out of ten," she said.
Sung's route to the showpiece final was more straightforward as she ousted Akane Yamaguchi 21-13 21-13.