I think you need to figure out the games you really want to have on the cab. 14" wide isn't much room. Even if you can fit the buttons, it won't be comfortable for two people side-by-side. Especially 2 adults.
Would you consider dropping the second set of buttons? If so, you can still keep the 2nd stick for 2 stick games (Robotron, Crazy Climber, etc.) and free up space for a spinner. Arkanoid and Tempest are great for a bartop.
Just watch your spacing for playability.