No, you don't have to reverse the 265 exhaust manifolds, you just use the driver side one on driver side, it dumps out between first 2 cylinders and avoids the steering box. At least that's how my 265 manifold is made. The driver side is the issue. If you've got room, ramshorns are nice too and don't require any maintenance, but they dump in middle (closer to steering box). You could likely use about anything on passenger side.
