Sounds like a reasonable risk to me... If you are independantly wealthy.
Buy the real thing.
Bill
EDIT, I understand it already worked on another car. My concern is the workmanship... I have built lots
of DB9 etc. type cables and they are prone to failure from flexing where the wire is soldered to the pin.
The only solutions I know are to POT the connections or buy a commercial cable. IMO, go commercial.
EDIT