Yes, the NeoGeo emulator that came out for PSP and GP2x runs everything from Metal Slug all the way up to King of Fighters 2000, I think you'd be looking for gnGeo for GP2X.

As far as Ghouls and Ghosts or Ghosts and Goblins, most of the capcom classics run on CPS-1. 1943, GnG series, Street Fighter I through Street Fighter II Turbo. CPS-2 supports stuff like Marvel Super Heroes, Marvel vs Street Fighter, Super SFII Turbo, and some newer shooters.

A good benchmark for a speed test of your CPS-2 Emu Port, Smoku, would probably be something like Marvel Super Heroes vs Street Fighter or Street Fighter Alpha 3. Those games should CRAWL on the SDL Mame emu lol! (But ran damn near full on PSP!)

Unfortunately I broke my PSP over a year ago and don't have GP2X so I don't know where the sources can be found anymore. All I know is that they were all done by the same Japanese developer so the code should be pretty similar for all of them.

Thanks for taking these projects over man! Good luck and if you need some info about proper speed/interaction on most CPS-2 games I have been playing Street Fighter long enough to figure out when things aren't right.