There was no water pump. We bought a used one with fan at ebay uk.
Water pump is dissassembled, only the casing can be rused.
Casing is cracked. That means that no part of the used but original pump we bought is useable. But meanwhile we could by another housing, which seems to be ok.
Second housing blasted and primed, no visible cracks.
We assembled the impeller on the shaft using the old bearing as a giude for the hammer. As it was invreasingly deformed in that process we had to use an old hammer head for the same purpose.
The protect the threads we srewed the original nut onto the shaft during hammering.
To adjust the end play we used a special part from Macs, see pictures.
The fan nut did not fit on the shaft. To reach the hole for the copper pin the nut had to be shortened.
The repro bearing cups of the front bearing did not fit into the housing. So we reused the old ones.