I did a 1967 Evinrude 18, a few years ago. Same cover as yours. I didn’t want to spend $50 for a cover seal on an engine, that if I tried to sell at an AOMCI meet, people would whine about spending $100 for the whole engine, running like a top. So I believe this is what I finally chose to use. It is not quite as full as the original cover seal but when you put the cover on, the latch is secure and the cover doesn’t feel loose at all.
https://www.mcmaster.com/catalog/128/4230
Style 3, Part number 8507K52
Long live American manufacturing!
