Best thing to do if possible is call the Engineer or Architect and discuss the plans. I know this takes time, but you def have to bis on what the other contractor is going to bid on. (compare apples to apples)
If you are going to be doing work w/this GC in the future and build a relationship you need to communicate with the parties involved. If that is unsuccessful I would walk away, I don't need the grief which comes with inadequate prints and lack of communication. A customer in my experience who is building, or having a building built for there business or whatever, is normaly interested in your input, recommendations and knowledge, which may also help you to land that job and a knew customer for life.
Good communication is key to a successful business. Sorry for the long windedness!
