Just pull the engine and tear it down . If all looks good regasket it . If things look bad you saved a lot of time and hassle. If you try to get it running as is you might just ruin the engine because of one cheap part or debris / corrosion inside .
this is good advice also I would think you'd want to see if a cylinder wall l has rust and pits. when an engine sits outside the cylinder with open valves take on more moisture than the others. Ive seen it real bad with boat engines etc.