Hit man, to be safe, if you have any doubt at all, use the old timer's trick. Put a thin amount of clay on the top of the pistons (should do all eight just in case), bolt on the heads with push rods installed. Hand turn (only) the engine so that all the valves have had a chance to go through an open and close cycle. Take the heads off and inspect for any valve face imprints in the clay. If you do have a problem you may get away with switching out the 1.6 rockers, just depends if, and how much interference.