as i said, it depends very much on the way you treat your engine. i now xt's which have done more than 100 000 km without opening the engine.
silver finished wheel rims? don't know them on 3AJ. as long as they are aluminium alloy, they should be okay.
kickstarter: is no big work since your right crankcase cover should have the boring for the kickstarter axle covered with a plastic plug. so all you have to do is to buy (second hand) the kickstarter unit, the drive gear, the decompression unit and some small parts whose english name i don't know. have a look to the pictures here:
http://www.xt600.de/xt_schraubertips...rter/index.htm