I don't think you need to run the 13.1 before the race. I would suggest getting a long run in before the race (8-10 miles) just so you're prepared for the run.The HIM programs I've followed in the past have had me doing up to a 1:50 minute run (longest in the training- for me that's about 10 miles). I would say to do a long-ish brick (maybe 30 min. to an hour off the bike). Just so your legs are prepared.
I'm no expert, but this is just based on my own training and programs I've followed. http://www.trifuel.com/triathlon-tra...n-Training.php