Some results for you.
Just before going to bed I decided to add 20ml (1/2 of the intended dose for the last wash) of acetone to the batch (this was the second wash) and put the pump on a timer for 1hr.
This morning I took a sample and did a 50/50 (250ml/250ml), this had a clear slit and clear water,
I added 4 drips of acetone and it stayed clear,
I tested it for soaps with a result of 42.56

To recap
180l batch, two stage non titration, clear 10/90 pass.
titrated acid wash with 30L of water, pumped for 3 hr, settled of 3hr.
second wash with 45l of water, pumped for 2hr, 20ml of acetone added and pumped for a further 1hr,
settled for 12hr, tests done.
The batch is now drying.
I have now run out of IPA so can't do any further tests for a while.