My 860 had an aftermarket vertical exhaust on it when I bought it but I converted it to horizontal shortly thereafter. I used it to mow and was routinely driving under tree limbs.
I believe that Ford offered the vertical exhaust for the 00 series but, I believe the cast elbow was used.
I see no reason why the large muffler elbow, muffler and remainder of the large exhaust could not be used with the original manifold whether 134 or 172 engine.
I have the large (horizontal) exhaust on my 64 4000 S-O-S and do not find the sound as pleasing as the sound of my 860 with small horizontal exhaust.