I'll add a welcome aboard also.
No help on the dollar value, but it's not going to be a very high figure.
It's true value is how much enjoyment you get out of the boat, how much it lights a fire to move up to a newer, more powerful boat, and the memories you can achieve.
Boating brings memories that you just can't get anywhere else, and brings families together.
Some of my best memories are just idling along toward the boat ramp for over an hour chilling with friends as the sun sets after a great day skiing and having fun. Don't remember any of the ski runs, or tubing runs, but that evening is burned into my memory. Just as freezing my butt off on a Christmas boat parade with a certain member of this board, who wouldn't let me drink any red wine, but was a gracious host to all aboard, and to someone who was lucky enough to be in town that evening.
Your google skills have led you somewhere useful, but not as useful as I'm sure you wished.
TriHull and 40 HP 2 stroke engines did go out of style long before I bought my first boat in 1988, so mid 60s sounds about right.