i love the same period ..interwar NWF in 20mm..
In fact they are some choices:
plastic Red Box Pathans converted/armed with metal more modern weapons - Sgt Mess, MJ figures, Wee Frineds hae in their list some nice Lee Enfields/Lewis guns ecc...
some selected poses from plastic ESCI Muslim Warriors armed/converted as above
my favourite choice is, in any case, 20mm metal Raventhorpe miniatures ...among their ranges, in my opinion compatible with everything, you can find niceties like RR Armoured Car, Vickers Light tank MK II, pathans from this specific period plus British and Indians with separate heads/weapons...their dismounted Sudan Camel Corps in turban and jersey are identical to the most characteristic unit in NWF for late period: the Frontier Scouts and similar well trained militia...also the wrongly designed Italian Colonial Dubat in baggy pants could well pass for a pathan