Insulating eaves above closed cavity

[Stevedore]

Existing house has no insulation around top of cavity wall. House is 1930s with a 75mm cavity which has been filled with polystyrene balls. The cavity is closed at the top with the middle row of bricks you can see in the photo. I have access as scaffolding up and roof being stripped and re done.
Not sure of best way to insulate- possibly remove brick bridging cavity and stuff rock wool into cavity so it comes up to meet loft insulation? Or leave brick in and stick with foam rigid insulation to side of top inside leaf brick and wall plate?
Any ideas or has anyone dealt with anything similar??

 

[Stevedore]

Will likely be fitting over eaves vents and those ventilator ridges to maintain air gap, just need to know whether to bother removing brick and best material and fixing method. Cheers!