Ok - ordered that B&S rebuild kit - went with the slow boat from China one as am in no huge rush to get this done:
https://www.aliexpress.com/item/4001240553571.html?spm=a2g0s.9042311.0.0.7fa74c4dGOl2kH

Not sure where most of those lil bits go - as from what I've pulled apart so far there's no that many pieces so perhaps there's some extra ones in there for other models. We will see.

Have the old carb soaking in a hot solution of citric and oxalic acid - the latter is used to clean up stainless steel so figured it wouldn't do much harm. Will see how its going after a few hrs and rinse off.