Hi Chris....
...we used a round wire brush in a drill and also a vibrating sander to remove what we could of the old, flaky paint on our 180 Lyc.
We first washed the engine with kerosene and green cleaner to get as much oil and dirt off as we could.
There are so many "lumps" like the top of the case, that it just takes elbow grease and also sandpaper in places and a hand held wire brush.
We bought original Lyc gray from ACS in spray cans and it turned out really nice.
Best,