To be clear, Magnum found extensive corrosion and pitting that went thru the hull. Could it have been fixed? Maybe, but it would have been a massive amount of work.
Instead he found a better project hull and completely redid that one.
If there is nothing wrong w the hull, regardless of the condition of the interior, sell it as is and let someone else make it the boat they want.
Hard to turn much profit on a 1 time, 1st time flip.
IMO, if a tin boat hull is sound, or nearly so, scrap is should never be an option. I like smaller closed bow runabouts like your Holiday and w lots of old boats for sale, it amazes me that people choose to buy a closed bow boat and 'convert' it to a fishing rig. Some w less then great results.
Good luck.