J K , I can't believe no one here can answer this?!?!?!?

Here's what I would do tho. Get an air chuck that seals the hole. Blow 10PSI air into it. 10PSI won't blow out any other plugs. Then just trace out the passage.

Does the air come out the crankshaft bearing feed holes? Chances are that is an oil galley hole. Probably does need a plug (installed correctly) may need two if there are two holes in the area between the plugs.

I would also go to the local chevy dealer or speed shop and request all the plug deallys needed to fill that *(%%^(^$ hole next to the bearing journal. Then pump them for more info as to the point of the hole.