What you seek may not be a factory standard item or even an accessory. BUT, that should not discourage you from looking
A hard used KG4 came my way minus cowl, but with an AJ23A carburetor with a combination choke and cover such as you seek, The screw holes lined up so the cover likely came from a Tillotson carburetor application without a cowl, Possibly a lawnmower , chainsaw or other small engine,.
By all indication the KG4 had been altered for some sort of competition and used quite a bit,
Hope this helps
Louis