A very basic check in the prop store Indicates that there are at least 4 different prop series listed depending on the year and motor model.
One Merc. listing for 79-83 actually mentions "Yamaha", Solas number 1511-145-19 yet if I go to 79-83 Yamaha no such number.
I do think that with the details of both motors there may be a match and one of our experts may be able to tell you what you need.
Otherwise get your details and simply search for props.Besides the different model years there are different gear case sizes.
