I agree with Spencer99's deduction that the PVs have much room
for add-on equipment. This could be done at short notice probably
before any event of hostilities.
Hulls 6 to 12 can probably mount 4 or 8 Harpoon SSMs at short
notice if needed. However, they would probably be just launch
platforms supplementing the firepower of a task force with assisted
guidance from the larger corvettes or frigates needed for
long-range engagements.
But just a sidenote that the MCVs are longer than the PVs, not the
other way round. The exact length would be 62.4m for an MCV versus
55m for a PV, as taken from Jane's. Each MCV is thus around 100
tons heavier than a PV.