Intake ports are about the same between LA and Magnum. Maybe you are thinking about the exhaust ports? There is a difference between LA and Magnum exhaust ports... bolt pattern is the same, but the floor of the Magnum port is raised for better flow. If trying to mate LA exhaust manifolds or headers to Magnum heads, I'd suggest using "Remflex" gaskets to make sure they seal at the bottom of the port.