If your tris are lagging you could do a lot worse than increase your dipping strength. Heavy dips are great tri builders. I prefer 'em to CGB. If you are using a heavy weight don't go too deep and put too much strain on your delts and rotator cuffs unless you know you are fine doing so. Focus on tris rather than pecs but at the end of the day, when you can dip for reps with close to your own bw hanging from a weight belt, your tris will no longer be a problem—it might well take years to get there though.
Do some extra volume over a cycle, like Totz said, and see how that works out.
Adding in a stretch-point iso for tris at the end of your w/o can also be beneficial. Something like overhead tri extensions. You won't be using as much load but you will be actively contracting over a greater ROM.
