I had my H31 out of the water for 6 months in 2013. I wasn't there when the boat was launched, but I went that evening to check on it. There was about 1 1/2 gallons of water under the engine that had come in through the stuffing box. It had slowed to a drip and stopped completely after a few days. I think the stuffing box had dried out while on the hard. If the boat you're looking at has been out of the water for four years, I think you should definitely replace the packing in the stuffing box before launching the boat.
You should also take this opportunity to ensure that none of the seacocks are stuck, and you should lube them while the boat is out of the water. You should also replace the zinc(s).
I wouldn't have any major concerns about the fiberglass as a result of the boat being dry.