Use a belt sander, fine grit and remove the chrome for about 2 inches. Then if needed use a file for your full mark and add mark. Remember to calibrate the dip stick if your using a non-stock pan.
Example: Canton Pans are 8 qt. systems, that means 7 qt
oil pan and 1 quart in the filter, not 8 quarts in the pan. The system is 8 quarts, kinda misleading.