start from runner floors first. its the easiest way to cut a little flow and not screw stuff up. read the directions carefully mix exactly. remember if it fails so will your engine . check with your machine shop i am sure they make repairs like this themselves. absolutely do not try this with the head on the engine .the head will have to come off as nomatter how good you are spreading jb you will still have to cut and blend the new floor contour to your head for it to operate properly. one more question did your buddy gasket/ port match the intake? this must be done to not recieve negetive engine effects.thanks