I just disassembled a 340 that I had rebuilt in 2005 and never ran . It was closed up in a garbage bag on a stand in the back of my shop which is nice and dry . It was abolutely perfect inside no rust or moisture at all . I had used assembly grease on the bearingas for long storage and that was still there. It would have been fine to run as is but i pulled it down for a cam swap and all i needed were new gaskets . Engine is in the car now and runs perfect. Also the rockers were not torqued down before storage.