HI Turnpike_Rat and welcome to this forum  
 
 You're right, Gauntlet Legends is one the best 'modern' arcade game cab'  
 
 Running Gauntlet Legends & Gauntlet Dark Legacy is a great idea, but you need 2 pcb, and a lot of 'Switch box', in order to swith all the wires ( video, all the joystick & button, credit, etc ... ). An easy task on paper, but a lot of patience for doing it  

Are you an DIE HARD arcade collector ? If you're a purist, you probably won't to destroy your actual control panel...
So why don't you buid the top panel like I did, and build a mame/daphne/computer setup... and it that way, you'll able to play anything  
 
 For the Dragon's Lair side art repro, this is the best place to go : 
http://www.arcaderenovations.com/store/home.phpGreat quality and... under OFFICIAL licence   
 
 By the way, can you post pictures of your Gaunt' cab  
 
  