Best of luck. Do you know the engagement in that painting? The headwear of the rank and file is very interesting.
74th Highlanders fighting at Assaye, in 1803, against the Maratha Empire on the behalf of the East India Company. The "round hat" and white trousers was common in the theatre even among the Scottish regiments, though they were technically permitted to wear kilts (and you'd think in the heat, they'd prefer it).