Used the Dremel and a fine abrasive stone to finish removing the flange from the circular cooling holes.
Trimmed up a piece of blue foam to fill behind the lower lip of the cooling duct inlet. Supposedly, if you leave that lip, it causes turbulence in the cooling air causing poor airflow through the cooling duct which, in turn, can cause cooling problems. I don't need cooling problems here in the Texas summer. So I'm adding the smoothing ramp.