Forward fish box drain (Update)

[CHANCE1234]

1972 20 SF.

The previous owner glassed over both the inside and outside holes of my forward fish box. I can't even tell where the original hole was on the outside of the hull. What is the easiest way to drill the hole in the original location. I would think the angle needs to be perfect so the flange of the tube lines up correctly both inside and out. The preferred method to drill this would be from the outside I think but I don't know the exact location to get the hole to come out where it should on the inside. Anyone ever done this or have any ideas? Thanks.