Jim, next time at least set the metal object on a rag or something so you dont scratch the paint. 
The white paint is pretty tough, it's a GM color. Now the Ford tangerine orange... that's a different story! It's chipped up all over the place!
Paul, I'm not running a plate underneath anymore, but I do have a washer and a nut under the easy one to get to.
Also, because I have the head shaved I make a steel shim to go under the mounting bar for the roller rockers so the adjuster screws thread the whole way through the rocker arm. Without the shim they just catch a couple of threads. Then, on the underside of the bridge I run a couple of beads of weld, then grind it down smooth to where it just rocks a little bit on the mounting bar for the roller rockers. I also drill the two holes in the head (the ones that hold the bridge down) the whole way down through the top part of the head so I can thread them the whole way down & use 5/16"x1" allen head bolts (the same size as the ones that hold the exhaust header on to the head).
