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

some guys complain about the poly, others swear by it. You might wanna do a search on those parts . I didn't catch if you got front disc or drum . BTW going from /6 bars to 1 inchers, holy cow , that's gonna be a stiff ride if you aren't ready. Was it factory sway or would you be adding that in?