An untoned kalitype print can get you in the ballpark for exposure but that is about it. Toning makes a tremendous difference in final print density, and even with toning there are significant differences depending on the type of toner and method of toning.
In my own work an untoned kalitype, exposure and other development procedures being equal, will actually have more density than a kallitype toned with either gold, palladium, platinum or selenium. So if I were to evaluate exposure on the basis of an untoned print I would generally increase exposure by about 25% for a toned print.
Note that my method of kallitype uses a 5% sodium thiosulfate fixer that has been made slightly alkaline by the addition of a small amount of sodium sulfite and sodium carbonate. Thus, altough there is some bleaching of the image during fixing the loss of density is not permanent as it comes back during fixing.
Untoned kallityes, developed in the sodium citrate developer, are very beautiful, with a rich, chocolate brown color. However, for image permanence kallitypes must be toned and I have as of this point found no way to tone a kallitype and retain the rich, chocolate color.