The message
from Tony Williams contains these words:

An old 3/4" flanged tap connector is near that.
I have one here. Measurements are.

Bore = 17mm. (5/8" = 15.875mm)

O/D = 20mm. (3/4" = 19mm)

The flange (which I can't quite get at) looks to
be about 23mm OD, and there is plenty of length.

That 20mm OD is the bummer.

Thanks but the bore is the bummer. I could modify the O/D if it didn't
force fit (it needs to be a tight fit anyway as the original has
locating lugs) but over 1 mm slack in the bearing is more than halfway
to where it is now. (Possibly I could shim that.)

Unfortunately I don't know exactly what you mean by a flanged tap connector.

--
Roger Chapman