Are suspension parts differernt for a V-8 K frame and the slant 6 K frame?

Agreed it is not always neccessary. For example, I used 30 degree equally clocked bars from 1989-2003 on my '67 Barracuda. But for the OP, I recommend using clocked bars. Even some people who are really into doing suspension mods are not always happy to deal with non-clocked bars (as we have all recently been made aware).