I got 2 coats of regular build gray 2K sprayed over fresh white epoxy a couple weeks ago. I decided to do a little blocking with 120 for a change of pace trying to fit the hood scoops on my 69 TA clone. I didn't spray a guide coat, just used the color/texture of the 2K as a guide. I did the drivers side of the car this way. Is this an accurate way to block? I have sprayable guide coat for the next few layers of 2k. Should I use a finer grit for my initial blocking?