Olympic and GlasPly with the deep V hulls are very popular on the Sound.They have a good ride in the chop that we get here.Both hulls are solidly built, so even a boat built in the 70's or 80's is not too old.The deep V is the thing to look for.
I would try to find 18' to 21' hull only and buy a new( or proffesionally rebuilt) motor.You are probably buying a bad motor anyway if there is one on the boat.Put on as many horses as the boat is rated for.You may need them someday.
I have a 16' Glasply.It handles fine but I would like some more deck space.
Around 20' seems to take the chop in the Sound the best.The difference between my 16' and my buddy's 19' is amazing.I think he is just long enough to be on two waves all the time while I'm hitting every one.
Hope this helps.Bigdog out.....