Here are pictures of my combined British Grenadiers. One base is painted in a style for East Indies Company and the other as the Grenadiers of the 84th (Coote’s Regiment), which arrived in India in September 1759.
Grenadiers would often be combined to form shock units, such as at Wandiwash in 1760 and Buxar in 1764.
Originally, I wanted the Grenadiers to stand out visually on the table. I thought using infantry in hats may not distinguish them enough – they would look like line infantry but without flags.
Information on the Mitre caps was difficult to come by. There is a nice two-part article in Military Modelling, based upon the paintings of David Morier, painted for the Duke of Cumberland c 1751. There was nothing conclusive for the 84th in the article, nor anything about the EIC (but that's not surprising, is it!?). Nor was their any specific information in A History of the Uniforms of the British Army by Cecil Lawson.