After reading the TSB about how to prepare the head/block deck surfaces, I pondered what I would use for a sanding block...

"For surfaces that have corrosion or pitting, wrap a piece of flat steel (4"x 2" or larger) with 600 grit wet grade sand paper."
I didn't have anything that would qualify as precision flat, so I contacted my fabrication guy. Here's what he was able to produce on his milling machine for me - a flat 1/2" x 3" x 4" steel block.



This was made from 1/2" chromium steel plate of the type used for silhouette targets.

I watched a YT video recently that showed what another guy used... a 6" long piece of angle-iron. That could work if he spent some time with sandpaper and a flat surface to sand it smooth and flat. He may have...