Trent,

The issue is deliverability. An implosion HEU weapon could far easier to mount on a SCUD with adequate range due to its lighter weight plus can have a much higher yield.

I still assert making the presumption that any Iranian nuclear weapons SHALL be a gun-tupe is foolish. Believe what you will.

Granted, most of the SWUs needed for HEU are consumed in moving from natural to reactor-grade. Starting with commercial LEU as reactor fuel would save them lots of time.