I have an 83 ProCraft with 115 mariner and I would say check with Shhip Shape Marine in Smyrna. No one around here including Clark Marine will work on my motor because it's so old and mechanics are trained on newer motors...??
He is very hands on so he prefers email. He will respond and get you taken care of. He also posts all repairs on his youtube channel if you want to get an idea of how he works before you go any further. YT channel is "Ship Shape Marine", and his name is Larry.
Email address:
shipshape@bellsouth.net
Good luck.