Work continued yesterday (after spending far too much time on the internet!!!).
I the slide bars installed on the motion bracket after slowly working my way backwards with the filing until the cylinders were in the right place.
you can see from the inset photo in this image how much I had to take it back. I did it in three stages checking the fit after each stage.
I shortened the piston rods a bit so that they fit inside the slide bars with approx. 2mm protruding from the gland on the inside of the cylinder. Now that I have it all assembled I will fit the connecting rods and cut the piston rods to final length.
The close ups show that I still have a bit of cleaning up to do.