Pittsburgh and Montreal discussing monster trade

According to Elliotte Friedman, the Pittsburgh Penguins and the Montreal Canadiens are currently discussing a trade that would implicate quite some big names and some big rookies.

With an ageing core, Pittsburgh Penguins general manager Jim Rutherford is reportedly seeking for a trade to help his franchise remain a contender for the Stanley Cup according to Sportsnet's Elliotte Friedman.
One thing the GM made clear: He is not interested in trading Pittsburgh's 2020 first-rounder, Friedman stated in his latest column of 31 thoughts. 
Friedman believes that if a trade were to happen, Juuso Riikola would be part of the deal. The Penguins have had an eye on maybe the heart and soul of the Montreal Canadiens, Brendan Gallagher. At 25 years of age, Riikola hasn't been able to slide into the Penguins lineup since being signed as a unrestricted free agent back in 2018.

Of course a Riikola for Gallagher trade would be just plain idiotic for Montreal. If you were Marc Bergevin, what would you be asking from Pittsburgh for Gallagher?