You will get varying opinions on this motor, here's mine.
To start with it's a 1971 model and has Merc's long gone distrubutor style ignition.
Parts are very difficult to find and often very expensive if you do find them (even used).
So, I would start with a compression check and a spark check - unless both are good I would 1) consider another motor if you plan on using the boat in the near future or 2) get a Seloc's manual and make this a project you can pick at or 3) part it all out and sell what's good to others trying to keep one of these models cobbled together.
This particular model isn't a "classic" that is often restored to preserve the look on an old wood boat and it's 65 brake horsepower makes it less powerful than a modern 60 horse (somewhere in the 57 horse range).
Given that a brand new 50 horse 2 stroke is still built by Merc and sells for a little under 5K if you look around, this (in my opinion) is definately not worth a couple thousand bucks of work to get it running properly.
If it needs nothing more than a bit of wire replaced and carb rebuilds that's one thing, but if it has mechanical or ignition problems that is quite another...