Originally Posted by
icepick_trotsky
That's a Silca pump. It is designed to mount the other way around, and the pump handle has a hole in the end that attaches to a brazed-on pump peg that most Italian frames of the era have on the back of the head tube:
On my Specialized touring bike ('84 Sequoia) that lacked this fitting I just put a zip-tie around the head tube and positioned the nub of it facing back so it holds my Zefal HP-X frame pump in place. That should work equally well with the OP's Silca pump.