is what you want. However, the stuff they sell at Home Depot and Lowes will probably not be large enough. Baseshoe is similar to quarter round, but it's not semetrical. One side is a little taller then the other, so that makes it span the larger gap from the floor to the baseboard without sticking out too far into the room.
You might want to look in the phone book and see if you can find a shop in the are that does custom millwork. They probably have the knives on hand to cut a baseshoe that would work for you, and it's not usually to much more expensive that the stock moldings you'll find in your box store. Good luck.