I think that'll still be too short.  Get a couple extra boards and do a scarf joint to make them longer. 
Have you ever kayaked before? A short kayak is not really fun for a beginner to paddle.  They don't track as well as one even a few feet longer.  If I was you I'd shoot for 10 feet minimum, but preferably 14. 
Yes. Ive been kayaking before.  And canoeing.  
