Iraqi scuds were monkey modelled jokes. Iran is five times the surface area of Iraq with extensive mountainous terrain, that's a lot of ground to cover. There numerous underground missile based located hundreds of meters deep. The difference is that Iran can design and mass produce them by the thousands. Iraq never had this capability.
The missile stockpiles would last for a while, if 25 were launched a day they'd have enough for close to a year. All the necessary production facilities are also located underground which makes wartime production possible.
That conventional military would quickly turn into an insurgency of unparalleled proportions, Iranian forces are asymmetrically oriented, they pioneered that type of warfare. The US has only got a taste in Iraq and Afghanistan.
