Agreed, true compression rarely meets advertised compression. 10:1 motors from back in the day landed in the low 9 range more often than not and the 8:1 smoggers go low 7s from what I here. My thinking it that if they did have a flat tops they might make good piston donors for some of the low mileage smogger engines I have. I bored at work so I am thinking too much.