early 60's gm fuel pump?

i've got the pump that screws together,but it's not marked for an inlet or outlet. its apart as i need to clock it back to clear a hurst mount. one hole heads up to into the pump itself and the other is a straight shot into the bowl below. which is which?

 

Put your thumb over a hole and press the arm against the workbench and see if it ****s.

 

i'm guessing the outlet leaves directly from the bowl.