The hard part was cleaning off the excess epoxy. I had used way too much and that stuff sticks to the steel real well.
I started with a die grinder to remove the Thermosteel that had squished out around the manifold. Then I tried various other methods to flatten the epoxy in the manifold clamping area. In the end, the best method I found was to wrap 80 grit sandpaper around a wood shim and sand the surface flat, by hand. It took about two hours to clean up the block.