So I went and took a look at this thing yesterday.
The bad news is its nothing more than a fiberglass hull, it needs everything. Transom is totally rotten but it looks like the easiest transom repair in history, the original transom wood is exposed plywood on the inside that is just glued to the fiberglass hull. So no grinding etc to get it out just replace and glass in a new piece. The two halves of the hull will need to be separated but that looks pretty easy, they are just pop riveted together and I would expect to have the top apart in half an hour. Restoration would be very simple. Also there is no flotation foam anywhere in the boat, so if I wanted to add some I'm not sure how I would make it work...
The good news is that there is no separate floor there are 4 pieces of 2x4 glassed onto the hull where the back to back seats were mounted and that's it. And yes I think you could fit 4 people in there but it would be tight, the gas tank is under the nose so the cockpit area is pretty much open, If i did build it, I think I would just build it as a 2 seater this time. Maybe even a bench with a little storage area behind for all the gear.
Here is my question, as mentioned above I have a 96 75 merc that needs a home, would it work with this hull? I can't see anything on the boat that says what the max power is and I know that it at one time had a 40hp on it. I'm assuming it was rated for 600lbs of people since the 4 seats. The tag is really faded but it looks like the rated weight is 3XX KG of load weight which puts it at 700-800lbs. So If it was built for two people that total 500lbs with gear, would the 75hp be too heavy? Looking at the transom I think I would want to mount the motor on a jackplate to bring up the height because the transom height is only about 12" before the hull shape changes, the motor would be buried in the water otherwise.