Re: 1970 evenrude triumph 60hp
See if he will let you take a compression and spark test. Check lower unit for water.
The problem is most likely ign or carbs, normal items for maintaince. Fuel lines could be coming apart on the inside, should be replaced.
These are only a guess, checks should be made.
The very first thing to do because it is so simple, is look to see what spark plugs it has in it. If they are still trying to run the surface gap plugs that were originally reccommended, trash them and put in Champion L77JC4 or QL77JC4. That alone has fixed the lousy running on many a motor of that year and size.
If it already has those plugs, there is a virtual laundry list of things that can be wrong with it. I was there when those motors were new and they were state of the art at the time. They also gave me a lot of these gray hairs that I have. There are better motors in this day and age.
I also agree with the previous suggestion concerning the basic condition of the motor. There is no point in beating a dead horse.