I posted the first question I had in the wrong part of the forum -
http://forums.sohc4.net/index.php/topic,175954.0.html and rather than compound the error (sorry!) I have moved the follow up question here.
Now that I have established that here in sunny New Zealand our "K4"s are in fact K2- s (thanks /u/jaytee-nz) it means I can look at the correct parts lists and diagrams and more importantly spend more money at David Silver buying bits - this time they should even fit....
I had a very difficult time getting the caliper arm to bits. It involved a 4lb club hammer, a big drift, and lots of penetrating oil. The suggestion to apply heat was a good one. I had a paint stripper gun (electric) and gave it a seeing-to with that. Eventually I got it to bits and I have cleaned up the pivot pin and the fixed and moving parts. it all goes together well now.
My question is this: The parts list I downloaded from this site shows that there are O rings and washers from stock. I dont have them. I will go buy some but I am just checking that they go at either side of the swinging part of the caliper with the assembly order between the fixed parts of the caliper being washer - O ring - swinging part of caliper - O ring - washer? That seems logical and a way to trap grease in between the pivot pin and swinging part of the caliper but I would be grateful if someone would confirm.
I have only 1 -2 mm of vertical play between the swinging and fixed parts of the caliper but I can always file it to get the clearance I need. I maybe closed it up a bit whaling on it with the hammer...... It was REALLY stuck though. took a day of soaking to get to a point where I could shift it sideways with the hammer. I hope that repairing this will assist with my brakes !