z-bar length question

Anybody know what length a z-bar should be for a 67 barracuda/360 small block? I have one that's 8 inches long and works after I modified it, however I'm having pedal return issues (that I'll figure out).

I bought a z-bar on eBay that was supposed to be from a 69 barracuda s340, but it's 9 inches long and doesn't fit. I'm thinking of taking about 1/2 - 3/4 inch out of it and adjusting the levers to fit my car.

Just trying to figure out what this is for/from?