I am looking for the white block you see primer bulb and rebuild kit for this.

I have had a look for you and this should be the flange you need: https://www.lsengineers.co.uk/flange-genuine-stihl-no-4241-120-2204.html and here is the carb kit listed for your machine: https://www.lsengineers.co.uk/carb-re-build-kit-for-stihl-bg86-leaf-blowers-4241-007-1700.html