[Mike C]

Rear leaf springs on your truck are 2 1/4" wide most likely while the square bodies are 2 1/2" so those won't work if that's the case.

You can re-weld spring perches and shock mounts and the rear should then bolt right in.

You can use power steering but will probably have to dimple the frame for clearance on your '67.

You can swap in the entire front crossmember for the matching 5 lug disk brakes.