(Reuters) -Indian conglomerate Adani Group plans to buy Holcim AG’s cement businesses in India for $10.5 billion, its largest-ever acquisition, to become the country’s No. 2 cement manufacturer. Adani Group, owned by billionaire Gautam Adani, currently has no cement-making operations but said the firms were a good fit given its ports and logistics, energy and real estate businesses. Under the deal, Adani Group will pay $6.4 billion in cash to acquire Switzerland-based Holcim’s 63.1% stake in Ambuja Cements Ltd and 54.5% holding in ACC Ltd, Holcim said in a statement announcing the deal late on…