I went through an engine replacement and could write a book about it. A horror story. I studied long block suppliers and picked one out. The mechanic talked me into using his supplier. He put in in the hold and discovered it was the wrong rotation. They rebuilt the engine in the hold instead of on the shop floor. Took me a day to clean out the beer cans and cigarette butts. I had to replace a lot of parts in spite of the fact it was a lake boat.
Your skills may bail your out. I got another boat with 2 low hours 318's. They run good now. I had to learn how to clean the fuel system, redo the carbs and distributers and redo the starting circuts. If the distributers need tiny springs for the throwout weights or you can't time the engines. If you can't time the engines the engine they will never run right. I wrote a lot of posts on these subjects but they seem to have gone to old post heaven.
Take your time and check out a lot of internet sources. This video is 7 years old but it impressed me and I called them for some tips.
https://youtu.be/72QwwG5X4XU or https://www.youtube.com/watch?v=72QwwG5 ... e=youtu.be
I just rebuilt the Starboard engine last year and bought one of the last reverse rotation camshafts that I could find. Good Luck with that. I found a used block to work with and did all but the carb work with the help of my son. I have less than $ 1000.00 in the overhaul. 400 of that was the new camshaft. Also with that being said i have decided to put my 1975 32' Sedan Fly bridge up for sale or part it out. The boat is located in Sandusky Ohio. Health Issues and Grand Children now stand in my way with getting it redone and back in the water. Let me know if you are interested.