Signs of rust in Engine any Ideas

Originally i used Royal purple for first start up , there is no breaking in for this flat tappet cam due to SM cermic lifters , you just use a good oil , The car has a twin snorkel scoop and a full 3 " exhaust , The car has never seen rain , or water , There was no water in the oil , There was gas in the oil pump when he tore it apart . The car is always under cover from day 1, last year when it was sitting we did get alot of rain previously to me having this problem , maybe it is possible water somehow got into the the carb , but you would think youd see the water in the oil.