Shimano 105 Rear Dérailleur noisy chain

I have just fitted a new Shimano 105 groupset exc. chainset and the rear derailleur moves up and down slightly and makes a buzzing sound when the chain is on big cassette (28t) ring and small chainring (39t). The chain is the correct length and the gears are indexed properly however it looks to be something to do with how far the upper jockey wheel sits from the cassette ring. I have screwed in the ‘b’ adjustment screw quite a way but it makes little difference.
All other gears work fine. The noise is worse when I backpedal so the freehub spins.
Advice on adjustments would be great.

I also have a slight clunking noise from the chainset under hard acceleration which I think is due to worn teeth as the chainset hasn’t been replaced unlike the rest of the drivetrain.