if you've got any dents in them push or plenish them out as good as you can then file flat. Take the file marks out with 80's grit on a block, keep going finer 120's - 180's - 400's- 600's -1200's -finally 2000's then they'll polish up easy.
Your buffer looks great. I use a die grinder with a mop on it and loads of water to keep it cool but obviously you need a compressor.
Looking forward to seeing the car this year, credit to you.