If this is an old (2yrs?) survey, and the owner has upgraded this could change things quite a bit.
You'll need a current survey anyway, and it should reflect any recent improvements. I doubt you would want to use the same surveyor again.....
Also, if $130K has been put into the boat recently, then perhaps the $27K difference you speak of is not a huge percentage of the price?? That may change the significance of the difference.