Based on boiling 6.50 gallonsliters at 1.042 for 60 minutes, this will decrease your wort by 1.00 gallonsliters, bringing your after boil OG to 1.048. You wanted an OG of 1.071. It looks like it will be under.
Wow. This beer didn't last long. It's been two months since I brewed it has been empty for over a week. I will be brewing this one again.