Problem with Mass Drivers is they are not great for engaging ships unlike MACs so Heavy Naval Gauss is probably the closest fit.
MAXC's in halo are difficult to use in fleet engagements as well. they are just the only thing powerful enough to punch through Covenant shields and armor. naval guass does not have the sheer size, power, and range the MAC's are supposed to have. Mass Drivers do.
Not too sure about the Sub-capital missiles the books especially describe the launching of the "Archer" missiles as waves of missiles
Archer pods fire missiles the bigger than a human. the size of IRL sub launched ballistic misisles.
battletech LRM's fire missiles the size of a human arm.
Sub-caps are the closest you get size wise
the array of 5 hatches are the archer pods:
and this is them in action:
the UNSC ships fire in massed launches because covenant ships (with their shields) are so tough.. a single Archer missile can kill a UNSC frigate.