I have heard that lapping them with sandpaper ruins them . . . don't remember the reason why and it doesn't seem logical to me.
The "real" solution was posted by "Carb King" and involved getting a FLAT piece of steel plate and mounting the carb halves to it using the mounting screws through holes drilled in the plate. Put the whole works in the oven and bake it and it is supposed to make the body flat again . . . only to warp next time you assemble it?
The best solution I have heard is to take the carburetor off and put it on a shelf somewhere and get a Carter carb.
