This guy contacted me - he’s got what he says is a new water pump to suit B27/B28. Said he’ll take $75 ONO plus postage (located in WA). Steve - Best contact is via SMS or ring 0410 137 487
This is where he bought it originally: https://www.autosurplus.com.au/volvo-260-262-264-265-760-water-pump-b27-2.7l-b28
And here’s his Gumtree ad: