I don’t know about your 60 but the J8C is to long
for my 75 Twist shift. They wont fit under the
cover and can short out the plug through the boot.
The original J8J not only had a shortened ground
electrode but was also a physically shorter plug.
If you find that this is the case with your motor
you’ll need to use a shorter plug.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.