LA vs Magnum

Heads: Can be used but must switch to AMC type lifters with flat tappets and pushrods to Magnum hollow pushrods
Cranks: Must use Magnum harmonic balancer as balancing weight is different so flywheel or flexplate is Magnum only Balanced
cams: Different snout with no provisions for fuel pump eccentric intakes: Very few choices to choose from but compatible with larger port 340/360 heads Bolt holes Vertical not angled many after market are predrilled to accommodate LA or Magnum
oil pan: Magnums we're only produced with front sump pans in trucks not useful for ABodies, pan dimensionally same as LA 360 at block mating surface

To be clear, stock Magnum pushrods don't work, they are too short. Just so no one thinks they can rob pushrods out of a JY motor and use them to put Magnum heads on an LA. I am sure you didn't mean stock pushrods, but someone might read it that way.

Mopar used to sell specific conversion pushrods, but I don't remember the length. I have a complete set but something like 4 of them are tweaked (bent) from the manufacturing process (I think). They showed up bent right out of the box, so I am betting the process of pressing the ends in bent the tube.