Sorry, I've been supper busy and missed in your last post a "query."
I don't do really well with just "words" to get an idea about what someone is wanting to do...So if you could post pictures of your stones, that would be great.
What I can share is that I have done what you are trying to do, quite a few times over the decades. Each case is a bit different and in the beginning I did it differently than I do today...
I would "bush" the stones clean and straight geometrically first and then turning when I had to do it all...by hand. Just like cleaning, sharpening or truing grist stones and related milling stones...
Now, its fast and much simpler to do with some basic stone carving tools under power...I take a 4.5 inch grinder with a diamond medium to fine shaping head, and while the larger stone is spinning, I register the grinder off something (?) solid and genitally lay it on the stone that is spinning. The process is done in usually less than a few minutes even seconds depending on how much shaping must take place...
Hope that helped? Let me know here or send me an email...
