Bellhousing runout '65 273

I need some help understanding the FSM on correcting the bellhousing runout using offset dowels. The FSM example covers runout at .020" measured with the dial indicator, but then states, "in this case, the housing is off crankshaft centerline .010". How is that? If the runout is .020", how can the crank be off .010" when you just measured .020"? The drawing then shows the offset pins installed opposite the runout, which makes sense, but how would a .007" offset make up for the .020" you just measured?

2nd question, is it easy to remove the factory dowel pins from the block, do they just knock out with a punch? Since I have the dial indicator, I'd like to install the offset dowels myself, but would hate to get the engine back here only to find out the dowels take a special tool to remove them, if that's the case maybe I should just have the machinist R & R the dowels. Thoughts please.