My rule of thumb for stock removal razors is that the total blade width should be planned as 4x the stock thickness, i.e. the spine thickness. So 3/16" spine thickness is good for a 6/8 razor, in my book. I shoot for a finished bevel angle of 16 to 17 degrees. Most commonly used razor steels will support that just fine if you don't grind too thin prior to quench. Your 8" contact wheel will do fine for initial hollowgrinding, but you will want your 2" wheel to push the hollow higher up into the spine.

Nice job on the pattern welding. Nice appearance,.unique.