If Petry were willing to go back to EDM, he would be worth Bouchard, pretty much straight up. So for Kovalchuk and a second (and eating the last month of Gagner's contract), you're thinking Pulowaljujarvi and a 1st rounder? Prepare for some heated blowback from the Prairies.

Colorado looks a little thin, but I don't really know Kaut value well enough.

Avs add; Oils add, nobody wants Poojarvisbust, add a real A prospect

Petry is still worth more than just Bouchard in my opinion. I know there is a HUGE age difference obviously, but Bouchard is still an unproven prospect and I think Edm values Broberg more.
For all anyone knows Bouchard can be the next Beaulieu, who's lucky to still be in the NHL. He should pay half his salary to Big Buff but that's another subj.

There's an aspect you're missing which is the opportunity cost of Petry over Bouchard. Freeing up nearly $5M gives the Habs the freedom to chase players like Pietrangelo AND Hall, while still having a great prospect to develop.