I dont think it will work if you fix it for the following reason: When you tone a kallitype yo do it before you fix it, to prevent fading of the image. That tells me that the silver that forms the image needs to be in some ionic state for the process to occur, or at least to proceed better.
Sure some people tone the kallitypes after fixing, but I get the feeling that the "fix" step is not really a complete one, after all you only put it in fixer for a few seconds a minute at the most. The tonning step has to be carried out to improve permanence, so this to me indicates that "ionic" unreduced silver has to be present.
As you say, we might have some excess silver, but perhaps this is not a bad thing, remember pd has a valence of 3 so it will require "more" silver to make a full image.
Of course all this is conjecture, only making a print and trying it out will tell the tale.