Leaky Holley Main Body (porosity?)

I've developed a leak in my old Holley 4779 750 DP. It's disappointing because this thing runs really well.

Any idea what could've caused this? I've had it apart several times recently trying to figure this out, but can't seem to nail it down. It's to the point where if the car sits for over a week without running, the primary bowl will drain completely.

I'm thinking it just be seeping from the main body like a porosity issue or something. Have any of you experienced this before?

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