I have milled a set a 6x-8 heads about 52 thou. i checked and found that they are at 87cc. Now if i am measuring right who knows. I filled them with water and measured it with a syringe. On a set of regular 6x-8 i found 101cc. Maybe some of the eggspurts will help us out. by the by i milled the whole surface as i did not know whether to mill the intake or exaust. Hope there are no manifold problems.
if it aint fixed don't broke it