Its impossible to tell the characteristics of the board I'm afraid, even if we have a picture of it. The characteristics depends on the shape and size of course, but the board would handle completely differently, depending on the surfer riding it.
Your experience level, height, weight, and the type of waves you surf in, are all big factors in this equasion.
I'm not a light fotted fellow (at 77kg's) but not heavy either, and one of my best mates is around 65kg. We have exactly the same amount of experience and surf on the same level, but our styles differ quite a lot. I once surfed one of his board, which I completely HATED (thought it was sluggish and couldnt get the thing to respond), but he still swears till this day, that its his best board ever, beeing quick, and sharp
Do you get what I'm getting at ?
I would always reccomend getting a board custom made, and be honest with the shaper about all the information he will be asking you.
Unless your a relative beginner, in which case board characteristics would really matter all that much
Hope that helped
if you are after basic characteristics, well a 6'4 in my opinion is perfect for someone who hasnt surfed all that long, and since you surf around here in the UK, I can safely assume that you dont really ride hollow waves much, in which case its good that your board doesnt have much of a concave.
A square tailed board, is pretty much an all rounder, but you wouldnt feel the difference at your level. I personally have a rounded squash and a Fish tail (not a fish board) The fish slides around a lot, and is fun to play with in smaller lumpy surf.... but kills me in hollower surf....and thats when I switch to my rounded squash