Just a thought some of the northstar matabele wars figures would fit in quite well too though they are for first war not second and seem to have martini Henry (similar to the zulu war Boers)
On the perry and Foundry they are compatible size wise as same scultor. The Mafeking figures would make a nice Urban commando.
I gamed this a good few years ago using Foudnry regulars and Hihglanders with some of the old glory Brits and art mixed in. They do tend to suffer a little form the weird articulated neck syndrome.
I didnt get their Boers other than artillery and made use of the Foudnry Boers with some BTD (though they have a bit of a funny pose and martini henry rifles)
The good thing with boers is you dont need a huge amount. If you do really fancy it it may be worth going down a scale to 15mm
as for larger actions the battles were often long range affairs with the Boers typically scoot and shoot once the brits got ready with the cold steel. It is na interssting period but for the wide open veldt 15mm in hindsight would be better to enable large battlefields.
Bitter enders and the blockhouses would be the way I would go for skirmishes etc