Are you sure about the cc's on the heads? A little quick research indicated that the 6X-8 heads should measure about 114 cc's. The 98 cc number you use would be more accurate for 6X-4 heads. I have a perfectly good set of 6x-8's in my shop that I replaced with higher compression heads. If it were me buying it, I would not plan on using those heads. I don't think you will like them very much.