Throttle Cable Help.

I'm trying to install the carb. linkage on my Demon 750. I have what appears to be the stock throttle linkage that came on this 70 Chevelle, but I have learned what appears to be factory sometimes is not. From the firewall to the square part of the line it measures 14", that seems to me to be too long, when I get my bracket to hold that square thing (don't know what that darn thing is called) I'm afraid that the rest of the cable will have a big loop in it that could bind. Can any of you guy's go measure your throttle line from the fire wall to that square part and let me know if this is off of another car so I can order the correct throttle cable.