There are two methods.
One is buying the rift lake salts to mix in the water. Don't let the word "salt" mislead you, these are the natural salts of minerals such as calcium and magnesium (primariloy, with some others), not common table salt which is sodium chloride and should not be added to these fishes' water. You need to mix the water outside the aquarium, so that means at every water change you need a container in which to prepare the water before it can go into the aquarium. GH, pH and temperature need to be the same or close.
Another method is to use a calcareous sand substrate. These are available commercially, intended for rift lake and livebearer tanks. They are composed of aragonite which is calcium and magnesium, and these minerals very slowly dissolve. These substrates last for years, probably decades. I used this when I had a tank of mollies and another of rift lake cichlids back in the 1980's and my tap water was very soft (basically zero GH and KH with a pH below 5).
You are not in a bad position here, because your water is at least moderately hard. You can see what the other members with more experience with rift lake fish suggest as to how high you should go, if at all. As I said, using the range of 160-320, you are not far off as it is.
BTW. does your well water go through any type of filter? I ask because some of these can add substances to the water that might not be good for fish. The other thing is the tank size, and the other needs of these fish, depending upon species. It is as well to have the whole picture.