Mike, when I ask someone their draw length and they say 30 or 31" my next question is "how tall are you?" If the guy 5'10" then I question the long draw. I ask if they've ever had their draw length checked. Some will actually say no but my other arrows are 31"
I then tell them to have someone mark their arrow at the back of the bow (be specific which side is the back) or they can do it themselves with a clamp on clothspin moved on the shaft until it touches the bow when they're at a NATURAL full draw.
If this person does in fact have a 31" draw and his bow is 65#@28", he'll be pulling 75#. That with the fact that the arrows are so long he'll need as heavy spined as you can get, 85-90# at least. If the bow is 65#@31" he'll still need 80-85#. Also ask what kind of string is on his bow, fast flight or dacron. FF needs a stiffer arrow.
If he doubts you forward him the comments on this thread.