My buddy has an Overnighter with an early 90's hull. This was about the time Grady changed the hull design for an improved and drier ride.
He is running a 200 hp 2 stroke outboard motor, seems to be the right power for his boat. It's an awesome boat to fish from, handles the chop very well and is very stable. The cuddy would be adequate for sleeping if you aren't a big guy, most of the time it is used for storing the gear.
I've have read on some websites that Gradys with the pre 90's hull had some stringer/ transom rot issues.
As with any manufacturer, a boat of that age should be thoroughly checked for rot before buying it.