Here's my timing map. I can still get some knock on spool up (GSC S1 cams) so you could try this and maybe even reduce timing a little in 2500rpm 100 to 260 to see what happens.

 

I would pull timing until knock decreases, fix your wideband, and optimize the fuel

 

it looks like pretty agressive timing, start there, pull back

 

Just for grins, pull your plugs and look at the piston tops with a bright flashlight, make sure they are all the same color. If ont is significantly lighter in color than the rest you may have a bad injector on that cylinder. One of my stock injectors went bad at about 20,000 miles.