So I had coolant mixing with exhaust AND coolant mixing with oil. Radiator was loosing pressure under test and the infamous white smoke was near suffocating. Tore it all apart, and the gasket shows no signs of being blown or cracked. The machinist looked at the heads, and they were flat as can be. Nothing wrong with the valve seals and the block shows no signs of being cracked. Could it just be a fluke? Could the gasket actually have gone bad without physically showing it? or could it be something with the lower intake ( I highly doubt it though)?