Well Red if its any help when you get your 7 fter shaped ready to surf . Dont worry i will take you to a special reef and give you all the verbal support you need to go and charge it and then I will let you know how well the board goes from watching you from the safety of the beach.I have an unfinished 7'0" in the shed.
Problem is - once it's finished I'll have no excuse left for not paddling out when it's a bit sizey!
By the way in my smallest board5ft6 widest point is 2 inches back from center where my gun 6ft5 is 3 inches forward...Going with what red said has a lot of merit and is a good place to start when thinking about shaping your board