Brian Waters still played at a starting NFL level last year for one of the best run blocking lines in all of football. He got cut because of age and salary, though I think he may be willing to take a pretty cheap contract for a year or two.
My thoughts are that we bring in Waters and stick him at LG, and leaving Beadles and Franklin to have a true competition at RT. Whoever losses out the battle is a good fit to play the back up line spot since both have experience at tackle and guard. Not an ideal situation, but it's a potentially pretty affordable way to make our team stronger this year until we can draft another lineman or Beadles or Franklin are more NFL ready.