But now the question rises, how would they be able to do so? If I remember correctly, Nadir Shah died in 1747, while the Qadjars (I'll refer to them as Qajars since I'm used to that name) came to power in 1794, with the first conflict between them and Russia being in 1796. To answer the reason as to why Persia was unable to support economic development was because, sometime after Nadir's death, Persia was divided in a civil war over who would succeed Nadir Shah, and that led to the creation of two rival dynasties, of which both ended by the Qajars.
For Persia to achieve economic stability would require the butterflying away of the Civil War. (which means Nadir would not be assassinated) Of course this would mean no Qajar dynasty, and that would probably ruin the point of this idea, but it is the earliest POD for a more powerful Persia, in fact it would successfully ensure Persia's role as a rising power and bulwark between the Ottoman Turks and the Mughals in India.