you may have better luck using the old wire (cable) as a sample for a prototyper or mfr of cables to make a duplicate. i know that some here exist in canada from equipment shows i have gone to, perhaps you may find some in your country. if not, you may consider a mico-lock brake valve, that is a releasable check valve that when activated allows you to pump up and lock brake pressure on, then release it by turning the handle lever. but the wheel cylinders must not leak! and you must comply with local regulations