That is exactly what I thought.
On the other hand, the great bulk of funds would come out of public sector development funds. This is problematic because HDI would get a hit. It would be worthwhile to tap the Army for a little budget cut. I am not an expert on security affairs, but a dent in public sector development would certainly restrict options to deal with militancy in future.
If the growth picks up further, and tax revenues keep pace with GDP growth, then this is doable. Otherwise, Pakistan would be stuck with a white elephant project. This is all the more reason to continue to push for institutional development and improvement of Constitutional systems. That is the only guarantee for continued growth and development. If institutions continue to step out of their domains, there would never be enough stability to pursue sane long-term policies.
The one good thing is to treat building of the dam and installation of expensive machinery as two separate issues. Once the dam building in underway, other countries and commercial entities would want to make profits by the selling machinery and services. Again, continued strong growth and stability is the key.