Here is a picture of the tool I made up when I did my first Bail A Matic water pump impeller job
The bottom outside was machine to just slide into the pump housing 1.692
The bottom inside was machined to 1.627
The top was machined on a tapper from 1.952 down to 1.627
the impeller fits in the top and rotated down to the 1.627 diameter
the to tool is fitted into the pump housing and rotated until the key slot lines up with the pin , push the impeller down , hold it down and pull the tool up
That was about 25years ago and it has been sitting in my toolbox ever since
