Removed from boat with a rotting interior with a Mercruiser 233 HP/Windsor 351 engine from 1975 production. Engine serial number is 4497247. Freshwater use in Indiana.  There are no visible cracks, but I recommend a more thorough inspection from a machine shop. Engine has never been rebuilt, but is being sold for the purpose of rebuilding. One freeze plug was removed for inspection. No gouging in cylinder walls, but some signs of rust. At this time, it is only available for pick up, as I don’t know how to safely ship this. I am centrally and conveniently located in Indianapolis, IN. Please let me know if you have additional questions.