check the tank, you may have a copper-top motor there. Evinrude built some of these with a heavy-walled copper tank that is virtually bullet-proof. if you have zero dings in a 70 year old tank, I’d say either that motor has been very lucky, or the tank is copper and not pressed aluminum.
Chips in the paint without corresponding dents or dings might be one clue.
Hope this helps.
Best,
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...