If you use the Sharpie,just move the pivot till your stone makes the most contact of the bevel.That is your angle.I have seen different batches of Grizzlies have slightly different bevel angles.you just have to find what yours is.If 30 degrees is taking the top angle more wouldn't you need to drop it slightly till it is covering the whole bevel?That is the beauty of the KME.You can adjust it to 30 1/2 or 27 3/4.It is infinitely adjustible and you should be able to match any angle.To be honest,I don't think anyone can answer that for you without being there.
Ron did some for me a couple years ago and I think they were about 26 degrees but I can't say if yours are the same.
Keep in mind,the actual angle changes depending on how close or how far the blade is from the clamp edge.I pay little attention to the numbers.The Sharpie and my coarse stone tell me how to adjust it.