External oil pump pickup pan mod...?

Anybody modify their own oil pan for an external pickup? Trying to save a few bucks since the Milodon pan is around $280. Plan on using a 12AN 90° bulkhead fitting but not sure of the hole diameter, sealing washers to use, or how to cut a "clean" hole. Milodon sells a fitting for this with the washer & o ring for $50 but I can get the fitting for $20. Just trying to save where I can plus I'd like to do as much as I can myself. Thanks in advance for any help.