Estimates are they have around 45-50 nukes, and I would not assume they store them all in one place.
I would not put too much trust into conventional military options either - when these options have had 6, and 4 years time to demonstrate their inability to gain control of lesser threats in Iraq and Afghanistan. Lacking success should teach us some more modesty, don't you think?

Also, pakistan, as well as Iran, would be a far more difficult target to strike, or raid.