(This all assumes the 220 is the same cylinder plating as the 200, I don't know if it is)d
The big decision is if you just slap in a new piston, or if you replate the cylinder. The stock (tungsten deposition?) coating isn't the best, certainly nowhere near as good as a Nikasil plating would be.
So your "worst case" in terms of agonizing over it is if you pull it and find a perfect piston a perfect cylinder bore. Then you can just put in a Weisco and call it done, or decide to replate. I'm guessing slapping a new piston in is at least $150 by the time you are done (rings, circlips, gaskets, bearing, wrist pin, etc).
Your "best case" for not having to agonize is to find a cracked piston and damaged bore. Then you *have* to rebore and replate and put in a new piston. On my 200 it was over $350 for back to stock, or $500 for a big bore and custom porting. A lot of $$, but at least you don't have to agonize over the decision, broken is broken.
The other wild card is piston life. My understanding from to the guy that did my top end (Eric Gorr), was that nikasil will let pistons and rings last a lot longer then the factory coating will... so in the long run, replating may be the cheaper option. If it saves one piston, you are already ahead.
You want to clean out all the KIPS stuff up in the head while you have it apart... and check for crank play. Since it's a two stroke, other then that, it's pretty simple. Not a lot else that can wrong up there.