Slant-6 and V8 linkage setups are not even a little bit the same. Pay careful attention to what you are buying (and who you are buying it from) so you get what you need. Here's what the '64-'66 A-body V8 throttle and kickdown linkage looks like ('67-up setups are not the same):
It's definitely a non-intuitive setup, and its adjustment procedure is a little bizarre. The FSM helps!