For the big Lump in the back. Highspeed cutting bit the kinda squared off one.
Also used it to take out some other material, namely enlarge bore so a 75mm TB will clear, and start the radiusing of the round to oval area.
Found Flap wheels made quick work on material removal and left a decent finish but they eat up quick.
The Drum sander bits go kinda fast ( not as fast a flapwheel) and are mediocre at removing material used in the raidus from round to oval area mainly.
Used the Rubber polisihing bits to get the smooth finish I was after.
Now I found a tear shaped cutting bit for an air grinder and it made super quick work of everything. On the other one I did then I just went back with a dremel with a flapwheel and called it done.