Can you use Ezra's abilities to change one of the heavy laser cannon shots to a crit? Not sure how these work.

I'm tempted to add ezra to my favorite

Dash Rendar (58) - YT-2400

Push The Limit (3), Heavy Laser Cannon (7), Ezra Bridger (3), Outrider (5), Engine Upgrade (4)

Yes.

HLC only changes the crits to hits when the dice are initially rolled, any other crits you can generate through modifying dice remain as crits.

However, if you're running Dash, you want Kanan or Kyle on board, probably Kanan.