When I referred to your setup, I was reading your statement: "In this particular case, I used a gray card, a medium blue poster board, and a dark maroon wool blanket all lighted identically. Of course only the gray card read 1/60 at f/2.8.". There's no reason to use anything but the dark blanket since that's the only thing that will be measured. It appeared to me you had used this setup thinking you were covering the whole spectrum from Zones I to IX and I suggested that couldn't happen.(posted 8500 days ago)Obviously you are headed in the right direction since you say your negs are getting better. Isn't that all you are interested in? It doesn't matter if the number is 100 or 500, if everything is done consistent and the results are repeatable. My TX35 number is 200, w/HC 110, and others have agreed you are in the general "ballpark".
Check your math again. The correct reading is .08 to .12 over film base plus fog. NOT 1.0. Use normal shutter speeds, e.g. 125. How did you get to 1/60th. If you started at 1/125 and f/16, and then reduced your steps by half stops, you should have gotten to 200, or even 100 long before you had to reduce your shutter speed. That's just another variable in your equation - the shutter speed might be off somewhat. It doesn't matter - if that is the shutter speed you will most always use! And remember, Zone I is not minimum density: Zone 0 is. There's only a minute difference [hence the .1 figure] between the two. You are using manual settings, aren't you? This is a manual test - don't let the camera do ANYTHING automatically.