From what I know, NSG is a permission to engage in nuclear trade.
Even if under some american pressure that the other members states agree to grant membership to Pakistan (Under american assurances of getting Pakistan to reduce its stockpiles and sign FMCT), this doesn't guarantee that Pakistan will get nuclear raw materials and technology from west.
The NSG membership will give Pakistan persimmon to engage in nuclear trade, but It doesn't force other nations to do nuclear trade with Pakistan if they don't wan't to do so. We also had these issues with others....ultimately, it was the trust factor that assured tech and raw materials.
If the Australian government refuses to sell raw materials, then NSG can neither ask nor force Australia to sell raw materials to Pakistan. The deal will solely be based on trust between Pakistan and other NSG members. Eventually Pakistan will be left with only China giving them what they want, which brings back to the question, why do they want NSG anyway? They are getting what they want from china already without NSG, even if they get NSG, hardly anyone in west trust Pakistan with nuclear tech, so they won't be getting anything from them.