From the Victoria's Wars Forum, Jf42:
Darrel, at the start of the war khaki kit was by and large sourced regimentally- or at equivalent unit level- and indeed by amongst individual officers as many group photographs show, particularly staff groups and Royal Engineers at Kabul in the winter of 1879-80. Others less so as the well known officer groups of the 51st shows. There are a number of oft quoted sources that refer to white drill uniforms being dyed with river mud. The results for some regiments were surprisingly smart, as in the case of the 10th Hussars, 9th Lancers or the 72nd Highlanders. Photographs from later in the war indicate more uniformity but whether this reflects a more centralised arrangement as some secondary sources have suggested, I think needs more research.
I have been gathering information on this topic on the range of khaki uniforms seen during the Afghan War, both in cut and colour, awaiting time to form into a coherent post. I am on the move with intermittent access to internet at the moment. If you can wait until next week I might be able to organise some of it to help you with your project. No colour photos of course!
Darrell.