Hey John,

To answer your question about the best route to follow, is for me quite simple.
I follow the approach of if possible to try to do as little as possible chemically to the tank. So for example, and this is really for example. I have a breeding set up for Apistogramma macmasteri.
The water I have out of the tap at this time of year is 7.8ph and a kh gh fairly low, about 8' roughly.
All I have done to get my tank stable and ready for these acidic loving fish is. Peat in the filter. Drift wood. And a very mature cycled tank system.
With the bio load on the increase I have to do some more water changes to keep phosphates down, But nothing changes other wise nitrate 0 nitrate .05 [think that is the right wording for api, brains getting muddles at the moment with reading red sea test kits.] ph with the peat and timber is a nice 6.0 and very stable. The kh gh is at the 3' mark they want. So far not a single issue with them at all.
They are healthy and breeding perfectly.

Now to come back and answer your question of the best option. IME if your choosing to medicate, the best option is to make the environment suit what the fish needs. That why the body of the fish is ready to destress, fill up on minerals and elements it hasn't got due to a different water parameter to what it naturally needs. Once you have done that then if need be the mediation can begin.
But first I would get the tank set for him to suit what they needs, which I see you have taken steps on. Which is very good. Very soon he will be up and at if all goes well.

I dot know if any one has mentioned it yet. But I use some lime stone to help keep the ph higher also helps raise the kh gh to suit as well.
Thats what I have done and am doing for my past and recent Tanganyika set ups. Which are quite similar to the Malawi.