Just picked up on this thread so I'm a bit late to the party. My first choice in this sort of situation would normally be to find the vehicle specific part from either the dealer or a factor or other source of supply. However if this proves impossible, and having an interest in older vehicles and machines this is not uncommon for me, I'm fortunate to have a branch of Pirtek almost on my doorstep.
https://www.pirtek.co.uk/service-centres/edinburgh/ Whilst they seem to spend a lot of time and are best known for mending hydraulic hoses on things like diggers and tipper trucks their branch holds a vast range of hydraulic and pneumatic fittings and hoses/tube work. Our local branch here are very helpful and keen to help if you go in with something unusual - I think they like the challenge of something different after weeks of probably doing fairly standard ruptured digger hoses. Almost as useful, and definitely as enthusiastic, are Forth Engineering
https://forth-engineering.com/ who are only about 15 minutes away in the car. Although useful for hydraulic and pneumatic fittings they are especially good at tracking down bearings simply by taking the old one in to them. They are also very good at recommending if a more robust alternative is available. In fact I'm spoilt for choice with George Browns just down in the docks at Leith too:
https://georgebrown.co.uk/ These engineering companies are not perhaps what we all first think of when looking for solutions to parts we can't easily buy over the counter but they are a godsend when you run into seemingly insoluble problems like this. I also find their staff are nearly always enthusiasts (often motor cyclists?) and very keen to be helpful.
So, if you can't track down the stuff you're looking for, have a search for your local Pirtek - or similar - branch and see if they are as helpful as mine. If they can help just take the old pipe in to them and don't worry about the quality or "robustness" of what they make for you - These guys are the "Pros" and really know what they are doing. A clutch hydraulic hose is child's play compared to some of the stuff I've seen them custom making to fit some old fork lift or back loader.