I'd jump on it. Very rare find out west. Tsunami/Sceptre are same boat, name changed around '75 due to a trademark dispute w Tsunami Boats.
'96 GM introduced the Vortex heads making for a more powerful and fuel efficient 350, er 5.7L. Same small block,but by most counts, better aluminum heads. Don't know if that's good for saltwater but maybe Mr Pelican or someone else that has one can tell you more. In a closed system it's a nice improvement.
Old F250 Powerstroke will pull it like a champ. As Connor suggested check the transom and the floors. Both very fixable. You will love that boat. Football field to fish from and shelter from the storm. Love my cuddys!
