That linkage is too complicated. What year was it for? What was the original setup ? Do you have the original linkage ?
I did a 340 swap on a 72 Challenger from a 318/904 Slaptick.
It used a single rod down to the trans. Because the 2 bbl carb sits in the middle of the intake and the 4bbl on the 340 has the primaries sitting forward. The carb/kick down linkage is too short. So is the manifold bracket to trans rod/transmission lever.
It was a simple matter of lengthening both rods the trans to manifold just needed about a 2" section added. The manifold bracket from a 4 bbl manifold.
If it is not for a "correct" restoration, the LOKAR kits work well and are very popular.