As things stand now, you only have a few choices with regard to country, and Zimbabwe is the most likely place you'll end up for a buffalo/leopard combination. Opportunities are very limited in South Africa and Namibia for this combination, Botswana will be closed by the time you go, Zambia is back online, but not for cats as I write this, Tanzania is expensive as hell, so that pretty much leaves Mozambique or Zimbabwe.
In Zim, you could hunt very successfully with any of several operators in the Zambezi Valley, Martin Pieters, Chifuti and Charlton-McCallum all come to mind. The Save Conservancy is another option, but right now they are going through quite a struggle over the land. There'll be some options in Matetsi, though I can't recommend anyone in particular. Keep in mind that most Matetsi buffalo aren't overly wide, though there are good numbers of them. Perhaps one of your best options would be in the Bubye Valley Conservancy. Check out John Sharp Safaris in the Bubye, though there are a number of other very successful operators in that huge conservancy. Lots of buff and very good quality, plus some of the very best cat hunting in southern Africa.
