Re: long trip with older motor
When I bought my boat it had a 1987 50HP Yamaha and I regularly took it 80 miles one way up the Winnipeg river alone at WOT, sounds to me like you need to gain some confidence in the reliability of your motor before you go on a trip.
Best way to get confidence is to ensure the motor is in good tune, new plugs, fresh gas and clean fuel tank, less than one year old water pump, clean oil in the lower end and a well tuned motor that starts reliably and boat wiring that ensures your not going to be stuck somewhere trying to fix a broken cable, add a battery that is properly charged and maintained and your there.
Make sure you have a spare prop and prop wrench, a good pull start cord, some spare plugs and wrench, leatherman tool and a flashlight, basic emergency box with flares and horn etc.
The distance your talking about travelling I don't even consider a "trip" since it is walkable if you were stranded, but a cellphone is a useful thing to bring along anyway.
Next thing you need to do is get some seat time close to the dock so you can drive for a whole day without worrying about it, once you gain familiarity with the boat confidence will come. To be honest having a locker full of electronic parts to carry around will likely guarentee those items won't fail and it will be something else that strands you...murphys law.
Give it a season, go out with your club and don't worry about being the guy who breaks down...the other guys won't mind towing you if the worse happens, just trim the motor up and hop into the other guys boat and go home...you don't have to ride in your boat if it dies! Besides there will be enough of the other guys around to lend a hand anyway if something goes wrong.
Stop worrying and you will have more fun, be prepared with the basics, keep her in good operating condition and enjoy.