Rob, you can only get one piston and one ring set anyway which will work for any of the cylinders. It's slightly small but should be within spec. I found this out the hard way (seized my SP and had to get help here) but was able to set up my racebike so it has less ability to seize (used the largest barrels I had). Anyway, if you leave the heads on, you can do the rebuild with new pistons, rings, and base gaskets. A top end kit will have a lot more in it including the piston pin, clips, needle bearing, head gasket, powervalve seal (I think). So what I'm saying is you can order everything now and wait till it gets here to take it down. It'll only be a can of worms if you've let a piston slap around enough to hurt a cylinder but you won't know that until you take it apart.

Regardless, it's a one day thing if you want to fix it. Just keep putting your fasteners back where they come off of, and when you go to reassemble it you won't believe how fast it goes back together.

Craig