That might work O.K. too, but actually, I mean to use a dark, contrasting color, like black or blue, red, and color the entire flange area. Then take the gasket and line it up w/ the bolt holes, and take the point of an X-Acto knife, or a sharpened nail, and scratch thru the color tp leave a shiny "scribed" line for you to follow along inside of...Machinists typically do this proceedure w/ a substance called Dykem Blue, it's a liquid in a bottle, w/ a brush - swab in the cap. It just gives you a contrast so you can see what you're doing better.