go to a NAPA store they carry those solenoids.
Johnny
Yes, the Ford solenoids will work. But here's the rub: Marine solenoids are grounded differently because they operate in a closed environment with fuel fumes present.
The Ford solenoid will work, but wont last as long. That's not to say I havent used one. In fact I carry one as a spare.
BTW, I have a 70 Johnson in storage for sale. I think it's a 74 model. It has been submerged, but will make a good parts engine or winter project. It has controls and prop, but no cowling. ( found cowlings on ebay). PM me if you're interested.