I agree with Glen on the overthinking part. I would not grind off the bevel you have. You are most of the way to where you need to be now.

If it were me. I would tape the edge that you have now, hold it flat on a flat hone and see if the spine is contacting the hone evenly using a marker on the spine. If you have even contact on both sides of the spine then you know that the spine is parallel to your existing edge.