I would be careful about Africa tan for NA mounting. I do not think processes are the same. We use wet tan for mounts, cannot ship wet tan to NA. Dry tan for rugs, floor throws and such, I hade zebra and back skins dry tanned in Africa for rugs that were nice. Not sure about tanning for mounts. I only do D&P now, when shipment arrives I send to the tannery here that I know and trust. When wet hides are done and I receive repairs, and mount. Once many years ago I did have a bunch dry tanned in Africa and sent as cost was almost same as D&P, until I received the rubber hides and had to send to my tannery before mounting. Wasted $$.
What you receive is what you get from Africa, we just sent a lion back for a "redo" as there was no stretch in hide. Tannery redid and returned much better second time, free other than shipping. Cannot expect that service from ocean away tannery.
I also say ask your taxidermist what they want/prefer and specifically his experience with Africa tanning and his specific knowledge of your named African taxidermist. I cannot say about Highveld as I have not used them.