Hard start conditions can be caused by something as basic as a single bad connection or as difficult to find as a weak distributor advance spring that doesn't always return the advance back to base timing for starting. Start with the basics- the things that can easily be tested and verified like battery connections (don't forget the ground wire at the block), battery and alternator. This sounds like the original alternator with a mechanical voltage regulator. This is one part that would benefit from a modern replacement rather than a rebuild. Chances are this alternator doesn't perform like it did 28 years ago. Probably the original battery cables too. I am not a fan of throwing parts at a problem, however, if the battery cables are original, I would replace them even if they tested OK. Replacing the ammeter in the dash of my '77 with a voltmeter is on the spring to-do list. They can tell you so much more of what is going on.
One thought...many of the alternators, mine included, need to see a sufficient rpm to get the field excited and producing full voltage. My boat needs to see approx. 1,200 rpm to get her fired up. I ran into a situation where I started the boat up, idled through a long no wake zone and across the lake to shut her down and chill for a while. Upon trying to restart, I barely had enough battery to get her started. Didn't see much happening on the ammeter, but a voltmeter would have shown the low voltage.
Two Chrome 10 hole wheels with Kenda Loadstar radials.
Mounted, balanced and delivered.
PM or email me for tire, wheel or package pricing.
CARBURETOR REBUILDING - $199
Parts, labor and return shipping included
2 LED 6" BRAKE LIGHTS DELIVERED $32