Rootberry, I've used a step wedge to do testing and have found it helpful in exposure, development, and film speed testing. Stouffer sells a 4x5 test wedge which will give you the information you need. It is calibrated in .15 density step increments (1/2 stop) from zone 0 to zone 10, so readings are done on the paper of your choice. Basic approach is to place the step wedge on top of a sheet of film in a holder, do the exposure, develop to see film speed and contrast, then print the test film on paper for a visual analysis. Since all you are really concerned with is the film's ability to match a paper's tonal scale, it gives you this information in terms you can understand. While the numbers are very useful from sensitometry, the paper is what you print on, not the numbers.
If you use a little thought and common sense, it will allow you to determine a very accurate plot of development times without a densitometer. Granted this is a less technical approach, but more information is available from one shot this way than with any other approach I know. Just do several shots with varying development times and then compare the results for your N+ and N- times. It takes a bit of practice to interpret results, but it works very well once you can see the relationships involved. A single shot is nearly useless in any analysis system, as it is the series of shots and different development times which give you the trends you need.
If you decide to buy a machine, remember to get one with a UV channel. Azo responds to UV light, so a conventional machine isn't what you need in this application.
You have left out one important variable from your posts, which film (s) are you going to use? Some are better suited than others to azo. Start with the 4x5 and tests and your 8x10 will be a pleasure to use. tim