it seems unlikely the oil loss is through the piston-wall space. That being said, 1 qt. per "70 to 80" miles is a very large loss, even for a ring-worn motor. Is the oil geting evenly into all combustion chambers? The key to solving this problem is the quantity of consumption (as there is no obvious loss). There are 3 other possibilities: 1) stem seals (unlikely), 2) crack in the head or 3) failed cylinder head gasket around an oil passage (this one would show prominence in one chamber).