Assembled

To ensure alignment when silver soldering I made a threaded gizmo with a bush to fit the pump end and added nuts to keep it all in place. I used some wire (actually a stretched out spring!) threaded through the base holes and around the gizmo to avoid any side-to-side rocking. Tippex was used as a solder resist around each end - last thing I wanted was to solder the gizmo in place!

Here's the assembly immediately after soldering...

When it had cooled the bar was removed and the whole thing dropped in some fresh citric acid 'pickle'...

There's a fair bit of excess solder that needs removing by file/emery but overall it looks ok - clean up time!