Parts list looks good, let us know how you get on when you get around to it.
I don't think Yamaha is worse than anything else in terms of the soldering work, hard to make guesses on the original solder used - obviously low lead content can be problematic which is why I suggested using 60/40 or 50/50 and making sure you add a little fresh solder to each joint. I think the heat is a big factor though, the better Yamaha amps (especially these Class A ones when run in that mode) generate a lot of heat, and in fairness the thing is 34 years old. The high-end amps prior to the switchable Class-A (i.e. only one bias setting) tend to run pretty high bias as well. Good for sound, bad for heat. Finally, unless you're the original owner, it's hard to know how it was used in the past - many owners stack other gear on top of their amps, a big no-no with these in particular.
Once you've done the job properly, given reasonable ventilation, the amp should last for a very long time.