Some more progress finally. Both ends of the stuffing gland were ovalised so I drilled them out 13mm and fitted brass sleeves. I'm waiting for another sleeve to bring it back to a 7/16 hole.
The 7/8BSP locknut arrived after weeks of waiting. This is a modification I've done to make the stuffing gland independently fixed and sealed with its own gasket. The wet end can then be removed without disturbing it.
The piston rod was bent and badly worn so I thought better to go the extra mile and make a new one.
The 11mm bar was a bit tight for the 7/16 Whitworth die.
So for the long thread I turned it down to 10.5mm
1.75" stroke
Final assembly and gland packing will be done when the extra sleeves are fitted.
https://techno.smugmug.com/Belt-driven-water-pump-refurb/i-J8zQgv2/ABrass is king