Dear Mr. Rat,
I think you may be getting a bit too technical in your approach. The test strips you are making are not of great value unless there is film in the picture somewhere. The normal test for maximum black is done (typically) in order to find the film base plus fog factor in a sheet of developed film. The characteristics of the paper and developer are dealing with the film, not just the paper.
Try using the edge of a piece of developed film as your contrast gauge. When this strip shows maximum black, you are in the ballpark and ready to try a test print. Print the film based on this exposure, then look at your highlights and see if they fall into place, are too dark or too light. This will tell you about your development for zone VIII values.