Hi Mike,
It isn't necessary to go sending your forks off halfway round the country. Any local light engineering workshop can do the necessary. You've fallen into a common trap which is thinking that you need someone who knows motorcycles to do the work. Not true. All you have is a tube sliding in some bushes. Dead simple standard engineering.
Most engineering works avoid motorcycle jobs for two very good reasons.
Firstly, all motorcyclists cry poor. I've never met a rider yet who didn't cry and wail at the very thought of opening his wallet. Or didn't think a fellow motorcyclist would be glad to work on his bike for free. This attitude becomes very wearing after a while and workshops have neither the time nor interest to listen so tend to brush you off before you can open your mouth. It is a business, it has to make a profit to survive.
Secondly, finding, purchasing and having delivered the raw materials to do the job takes time and costs before the job is ever started. All of which is added on to the final bill which makes for even louder moaning.
You get around all this by approaching your local model engineering club. Near to you will be some club that runs miniature steam trains in a local park.Ask them for advice. They will know who sells the necessary steel tube and bushing and which local firms are approachable. Any model engineering club has members who have been in the engineering /machine shop game all their life. They can provide very practical advice on what you need for your forks plus how to go about it.They are your best friends for this type of work. Much more so than the usual motorcycle dealership. You will also gain a lot of useful knowledge for other parts of your restoration.
Let us know how you get on,
Cheers,