He can be easy for Leon, Spawn at the tower area (if you don't go to options and click retry on continue point) climb the ladder to get the grenade, run to the zipline, Salvador should follow you. throw your grenade at him, if it hits him keep hitting him with your Riot Gun, if not, go down the zipline and hit him from a distance.
Alternatively once you meet him, climb a ladder, once you climbed it, move back and look at the ladder, once he jumps up his chainsaw should stop revving, then just keep hitting his head, he'll die easy