Elevator, full cheek snaffle, slow twist d ring
You may want to think about working on his sensitivity instead of moving up in bit intensity, you can do this by sitting on him and slowly applying even pressure in both riens until he gives, reward with release of pressure and continue this exercise until he begins to become more sensitive to the D but you have:) I hope this helps!!
It's so much individual. I using a Scorcer bit 😊
I do eventing and I use a French link with running attachments and my ottb is psycho, for me it just does enough if my seat won't stop with I can readjust! Good luck!!😊😊