It would appear that I've nailed it. I've not road tested it and from what I can tell the slave and the arm are going through their full travel.
I've still got the 3-4mm line installed. The pedal is firm, feels exactly the same to my old cable set up with the type one box and stage 1 KEP pressure plate just alot smoother.
I just need to put my engine back together and get it running and then I'll be able to test it whilst I adjust my cable shifter.
I've got a bigger line for the setup which I'll most probably install in the future to reduce the pedal effort but I'm in no rush to change it at the minute. It's fine as is just a little firm.
Sweeeeeeeet