That intake operates from 1500-6500 rpms, so it might be much for your 5.2 but i don't know of a smaller intake for Magnum heads. I think Mopar made one.
There is no Dedicated 318/5.2 intake for the Magnum. The ports of the intake are the same (close) to the cylinder head which is the same cylinder head for both engines.
MoPar did have there standard dual plane available for the Magnum engines. (The early 340 intake modified) They are not made anymore and were not that popular which makes them very expensive IF you find one. Pretty much the same rod there single plane intake for the Magnum.
@Miloburnz Use the Edelbrock RPM intake manifold. It is worth the price. I like ethers MSD or an Accel distributor.
With any vacuum secondary Holley carb, you’ll need a throttle arm adapter, secondary spring kit & jets to tune the carb.