Judging by the original paper tags on the lower unit of that motor I would say it has not actually been run in water since being crated & shipped to the dealer. Now it looks like it has seen a lot of humidity from decades of hot & cold cycles in an unheated garage. Given enough time and inattention you will see rust. Periodic sprays of storage oil would have been a great thing. I wonder if the piston rings & cylinder bores are rusty from the unheated storage conditions over the decades? It would be worth it to investigate before firing it up; in fact there are numerous things that should be done prior to start-up. What a nice motor though! Or in conversational Scottish, "Awk wee, it's a bonnie one!"
I notice that your motor is a manual start. You will need valor to start it, but at least since it is a manual start version it comes factory equipped with a decompressor.
Take a look at the attached picture of a brand new 1970 Johnson 33, noting the paper tags to proect it during shipping within its crate. Like yours, it is a manual start version. Hmmm, perhaps the original purchaser was saving face at not being able to pull-start their new motor...
