The hull is the same as on my 1976 Starcraft American. Designed by Waltman B. Walters, longtime marine architect of several prominent offshore V hull designs back in the day. The Merc 1000 appears to be a 1969 model, and though it's possible it's not original to the boat, it may very well be. Starcraft had the plain coloring at that time, too.
I'm going with the V-180 model, possibly 1970 (as I think 1969 still had the "lap" side look), which was the predecessor to the American series that came out in 1972. Same hull mold, slightly different deck molds. Walters designed that basic hull that Starcraft would use for the next couple generations of fiberglass 14 to 20 ft. V-hull runabouts, through the Medalist series of the late 1980s/early 1990s.