If I were the Prime Minister, I would assign the Ministry of Finance to Arun Jaitley, with Jayant Sinha being made the minister of state.
Both are highly qualified individuals and come from Modi's pro-reforms school of thought. Sinha's experience (IITD, HBS, McKinsey) would further help him engage foreign diplomats and industrialists to set up strong ties with the western world.
Arun Shourie who briefly held the Finance Ministry in Atal Bihari Vajpayee's government could be allotted the Ministry of Commerce, given his strong ties with industrial bodies. Such an arrangement would balance meritocracy and new thought that would propel India in the coming decade.