Here is the tool I made:
That was the theory anyway!
One of the shocks was put in a strange way, using a nail for a split pin, and the spacer on the wrong side:
Luckily, the aluminium strip part of the tool fitted in behind the top front shocker mount, so it ended up being a good session (see above).
Not so good was replacing the rubber spring shackle gromits - despite assurances they had plenty in stock, I went to collect them and found that there were only 11, of course you need 16 on a JB van. So, I have completed one side. Will have to wait until next week to get the others.
Incidentally, the people at the shockers place told me that the shocks that I replaced were pretty much identical to the "Toyoace" van of the late 90's. No-where near as charming as a JB.