Thanks Guys, yeh spoke with Paddocks and they say the 3/4 self adjusters are all that is available so I have sent them back. Disappointed that they don't say on the web site what size they are. But they did say on the phone that they only sell them in pairs, thereby acknowledging that they are wrong!
That first link looks promising, might be worth a punt at £50 , shame you can't see the backplate side to see if the handbrake slot is in anything like the same place.
Perhaps I should fill you in a little more about my requirements, I have a Mk2 from the USA and it came with some shi* split braking system that I changed to a single system with a remote servo. Much better, however I am not satisfied with the front to rear brake balance, it locks the fronts up too easy, particularly in the damp / wet. I have 3/4 manual adjusters at the moment and am quite capable of adapting things, I had considers boring out some 3/4 housings and making my own pistons as you can get the seals. However there isn't enough meat in the cylinder to do this. I'm sure I can adapt a self adjusting cylinder to a manual set up or at worst convert to a manual self adjuster like I did on a Sprint by just drilling a hole in the drum so I could adjust from outside.
Or are there any variations on front calliper I should look for ? There appears to be reference to metric and imperial, are the pistons different sizes?
Rob