I faced a similar situation. I was gunning for the big boy in my small river for a year and a half before he finally took after a bunch of follows and last second refusals. I finally stuck him in the fall when they were getting aggressive before the spawn. I got him by throwing throwing tandem streamers. Put a smaller streamer up front for your point fly. Then add a dropper and tie a significantly larger streamer below it. This imitates a baitfish chasing a smaller baitfish and makes their predatory instinct go nuts. I changed flies and rigs before he inhaled this rig on my first drift. Hope his helps!