I'm not terribly well qualified to answer this question, but there's probably not all that many other Travel.SErs who have traveled on the road in question, even a good ten years ago...

So.  From Mchinji in Malawi across the border to [Chipata][1], the largest town in eastern Zambia, is only about 30 km and easily covered in a day.  Chipata has a large [Shoprite][2] supermarket for stocking up and a smattering of guesthouses and restaurants etc; [Mama Rula's][3] is apparently still there and you could probably do worse than stay there, although it's a few clicks in the wrong direction towards Mfuwe.

[![enter image description here][4]][4]
*Which of these will be your future home away from home?* (pic by me)

From Chipata to Lusaka you're on the [Great East Road][5], which is the main highway connecting Lusaka to all points east.  There is thus a steady stream of trucks, buses etc and the infrastructure to cater for them.  That said, this is the African bush and there are *no* towns of size along the way, so you're not going to find anything approaching Western standards, but if you're OK with *[nshima][6]* and grotty rooms with a fan if you're lucky, you'll survive.  [Bridge Camp][7], around the halfway mark near an otherside pretty desolate stretch, is apparently still there as well.

Good luck!

  [1]: https://wikitravel.org/en/Chipata
  [2]: https://www.shoprite.co.zm/store-locator.html
  [3]: https://www.mamarulas.com/
  [4]: https://i.sstatic.net/26Nhn.jpg
  [5]: https://en.wikipedia.org/wiki/Great_East_Road
  [6]: https://en.wikivoyage.org/wiki/Zambia#Eat
  [7]: https://tracks4africa.co.za/listings/item/w147297/bridge-camp-luangwa/