Some of us that have done a lot of this stuff also know to take a quick look at gears dot to dot and check #1 cyl lifters to check for and even overlap of ex closing and intake opening. This does apply to most chevs and mopar v-8's, but certainly not all. I've corrected, as many here have, the 3 way screwups when friends use wrong markings and are 2 1/2 teeth off after their install. Goodys got it covered so it's done, right?