Update: the new cooper pipe is in and the new hose clamps have a tight fit now. Just did my first test drive and ended up in a sudden hailstorm

But after close to a year of restoration it was great to be able to start the engine again and give it a short spin.
If some 4/4 CVH owner doing a restore and running into a similar issue reads this thread in future: Go with the clamp that "Image" posted above. Stupid me had a mental "marriage" with the new wide stainless-steel clamps - the ones above would have worked fine I believe.
The solution with the new fittings works as well - but the hose at the end that is connected to the heater matrix above has a tight fit with the bulkhead. So, if you replicate my solution with a new cooper pipe with press-fittings, then add a 90-degree elbow piece at the end facing up. If you use a T-connector that is soldered to the pipe - you should be OK - the difference between the press-fitting and soldered version is a few centimeters. But as the pipe is attached with a bracket to the engine these will be exactly a few centimeters that will cause you grief....
Another advice I can give: If you need to replace or work on the clamps on the hoses beneath the distributor - disconnect the hoses from the carb, heater valve and above the thermostate to get out the pipe including the z-shaped heater bypass piece. It should pretty much look like the hoses and connections I had on my first picture of this post.
With a bit of luck - my next post tomorrow can be found
here 