If you want to rebuild it you need a way of measuring.
As far as balancing the rule of thumb is to mark it. The turbo is very easy to assemble I think a 5 year could do it. Hardest part is the clips lol.
Anyways you need to disassemble your turbo before ordering parts. They machine/bore turbos @ .005, .010, .015 so you need to know where you are first before ordering. Ebay kit is stock unless specified.
Basically remove a old bearing and measure it. If stock it will measure .625 when you measure the turbo housing you should get .627
Now when you measure the inside of the bearing you should get .394 and when you measure the shaft should get .392
After you have your measurements if you want post them so you can buy with confidence.
But now that you have your measurements and know where you are look for scratches. Use your fingernail on the shaft if u can feel it....it needs attention. If it's smooth all the way it's perfect. For the housing use like a ink pin or a tooth pick.
If it'd rough n has issues let me know and I'll tell you how to go about fixing it without a arm n a leg. Any machine shop can do it they just don't know the specs.