Some sensor involved in the timing perhaps? Any codes for a cam shaft position sensor, etc.? Lots of fuses to check.

 

Was the removed spark plug wet with gas?

Pull a spark plug wire off the plug, hold it close to the block with insulated pliers and see if you can visually see the spark jump from the electrode of the wire to the block. Maybe good to do at night or reduced light conditions to aid in seeing the spark.

I would be very hesitant to drive it to West Coast and back if it is not 100%(or close to 100%). If it craps out on you in a bad location, that would be a bummer. If it ain't right, I would go with a rental vehicle for the trip. It would be a shame to be stranded in a desolate location with a broke down Disco. Unless of course, you have the big fire, loud music, meat, drink and the scantily clad women to make things bearable.