Here's some more to think about;
Arabian (Z80 , AY-8910 sound)
Commando (2x Z80 , 2x YM2203 sound)
Gyruss (looks complicated, lots of CPUs)
Juno First (Z80 etc. , AY-8910 sound
Karate Champ (2x Z80 , AY-8910 sound)
Rescue (2x Z80 , 2x AY-8910 sound
Son of Phoenix (2x Z80 , 2x AY-8910 sound)
Star Force (2x Z80 , custom sound)
Vulgus (2x Z80 , 2x AY-8910 sound)
Wall Street (looks complicated, S2650 CPUs)
Xevious (3x Z80 , Namco sound)
Good luck you brave, brave men.