If you knew of someone with a Standard Venture parts bike you can get the lines you need, I have done that with a couple that I had, got tired of messing with the contoler,
You can take your lines out of the front forks and make a your own a line to eack fork with a tee fitting in it so you can inflate both forks the same.
Try ebay maybe find the parts that you need, I will dig threw my parts and see what I can come up with may have the line that you need for the rear.
If I have it just pay the shiping and its yours
Orlin