crap shoot meaning..
..I don't know what you'd get. The numbers you list being .015 apart, certainly one size would
NOT fit all.
Probably a piston that was within specifications, but not one that was optimally fit to your cylinder.
With the piston-to-cylinder clearance being measured in .00x, and the piston tolerances being 1/2 of ONE thousandth, there's a good bit of wiggle room.
If you prefer (as I would) to have the best possible fit for the highest return possible (moh power), putting an 'I don't know what size this is going to be..' piston into your cylinder isn't going to accomplish that.
As long as you're going to the trouble and expense of a top-end, why not do it right? ...or as right as you can, anyway. The gasket set costs just as much if you put in a sloppy fit piston as one that fits correctly. Just as much mess to cleanup, too!
I don't see a kdx220 on Pro-x's product list...but they DO say it's only a partial list, so contact them if you want to know about 220s. I'll bet they do make a piston for it.
http://www.pro-x.com/form.html
will take you to a screen that you can ask them if you wish. Also a dealer locator.
BTW, I'm not advocating pro-x as THE piston to buy. Just that they make pistons that actually FIT into different kdx cylinders. You won't get that from kawi..you won't get that from wiseco.