Looking at the first set of pictures, it seems that the 307 piston sits down in the bore more than the 250 piston. I guess we will know when they get measured. Do all of the 307 pistons that you want to get rid of look like the one in the picture? If they are like the pistons that I see around here, the 307 will have a pin height of 1.655 and the 250 will have a pin height of 1.640. That should make a .015 difference.(A little hard to see in a picture). To me at least, this is very interesting because I have heard as much about 307 pistons as I have the 194 head over the years. The wonderful thing about this site is sooner or later the facts come out and myths are dispelled. Jay 6155
