hard to tell what is in that hole from the picture. spin the
oil pump with a drill and see if
oil comes out of the lifter bores. if no then they might have it plugged in another location. to the right of your cam in the front of the block there is an access hole, to the
oil galley plug. this may be a pressed plug or a pipe plug. behind it there may be a plug pressed in there, it would be about
3\8 in diameter, this blocks the left bank. also check the rear of the motor, at the cam plug
are there two removable plugs at 10 and 2 o'clock if no then its not a hydraulic block if so they might have the galley blocked there.