FWIW there's a used complete dry-sump system on HH for $1200 right now.

If you can't afford that you're in the wrong class.

The lower oil drain backs you see at the lower corners of the cylinder heads (under the valve covers)still drain into the valley. There are no secret oil drain backs that don't go through the valley. Ford, Chevy, Mopar, race V8 Toyota, etc.