The Walbro book says the SDC 40 carb was made for a Lombard chainsaw, but the chainsaw book says the carbs used were either Tillotson or Walbro WA, not SDC...
The K and S are the symbol of Kolbenschmidt, the company that made the cylinder...The B on top of the cylinder is for sizing the piston mfor piston to cylinder clearance....There usually A, B, and sometimes C pistons..The sizes are only about .0003 apart, but a C or B piston should not be used in an A cylinder...I have a few old engines here, maybe I can find a match to the cylinder...