I went over the remaining oxidized area with the black compound and the sisal wheel. Afterward, I spent 2 1/2 more hours with the green compound and got this area polished up. The bluish streak running from upper left to lower right is witness to the scratches left by the green compound. They catch the light from the camera's flash. Those should pretty much disappear after going over these areas with the blue compound.
I'm estimating about 10 more hours until the firewall is done. Then it's on to the firewall recess and the heater box.