G'day Andy, I've just finished cleaning, painting & re fitting mine on the Ambulance.
I was fortunate enough to have 4 of the long ones & one of the short ones NOS in the shed
The remaining old ones were easy enough to clean up providing you have a wire wheel, a commpressor & air nozzle
I tip some metho or petrol down one end with a primus lamp primer ( a small plastic bottle with a metal tube spout) and blow it through with the air nozzle two or three times, if it still looks dirty inside, use the wire out of an old bonnet pull cable & give it a clean out with that, then the metho again.
When it's clear, clean off all the crud with the wire wheel, being careful not to catch it on the wheel (I ended up with a corkscrew on one of the small lines
)
Then inspect the line for any crushed or damaged bits & if ok paint with Wattle Epoxy Alluminium, if any are bent out of shape, try refitting them before painting, they bend easily
Failing that, do what Stapla did & get the brake place to make them up for you, but be sure to tell them the threads are imperial, not metric
Good luck with it