We tried to install the throttle cable and ran into a snag. I bought the Mancini MRE 8408 throttle cable that they advertised as being for the 70 Challenger with a big block. It is WAYYYY too long. It is 29 inches. I found the junk one that we took off of the car, and it seems too long too, but is the same length as others that I see for sale (22"). Is it normal for it to be this long and need to get a big bend in it to take up the extra length? Also, I need to know how the clip at the end of the throttle cable connects to my carb which is a Holley.
It looks like you need a Holley throttle lever extension and a carb linkage stud.
Carb linkage stud
https://www.megapartsusa.com/products.php?cat=179
Throttle lever extension
https://www.summitracing.com/parts/hly-20-7?seid=srese1&gclid=EAIaIQobChMI6seN75ev_AIVGcmUCR3ZogswEAQYASABEgI3TvD_BwE
Why do you think it is too long? It's hard to tell from the photo but it looks like it is just a bit past the carb. If I recall correctly it is kind of like a bike cable where it is anchored at both ends and the actual wire can be much longer. If that is the case, then it looks like you might just have some slack. Is the wire excessively longer?