I like the 555 a lot, especially the fact that it has the small bar mount, nice lighter 60 with all the modern features.
You should have it pressure checked before torn down, then you'll know how deep the problems are. If you don't have a great dealer to support you it may not be worth your trouble. Also depending on the yr I wouldn't mess with it, pre-2016 I'd sell it or trade it for parts for the others.
This
, but to make the job easy you should also use the carb/intake.
The 371 single ring is the kit that many like if you can find/order one.