Both can work with manual steering, but neither is a "drop-in".
Both will require varying degrees of grinding on the manifolds and/or trimming back the steering column outer cover, or replacing the coupler with a smaller diameter u-joint, and shimming the motor mounts for clearance. Or in the instance of Magnum manifolds, Shaving a bit off the mating surface to gain a little extra clearance.
This is all on the driver's side; I have never seen an issue on the passenger side, outside of some people reporting that they had an issue with the "swept back" passenger side 340 manifold contacting the firewall of early As.
Then there's compatibility with whatever motor you're running- mainly if you try to run 340 manifolds on a Magnum. There's a port mismatch there (the 340 exhaust manifold ports extend down significantly lower than the Magnum ports and have been known to cause sealing issues in some instances).
Lots of threads on here about fitting 340 and Magnum manifolds, and the sealing issues if that's pertinent to your situation.