A shorter rod and longer piston means the wrist pin will come to a lower point in the bore. I would run the 500 and get a kit with the longest rods. Longer rods put less side load on the piston and the overall height of the piston (Crown to tip of skirt) should be the same. If you are dead set on a 7000 rpm motor though then get the 470 and still use the longest rods you can.

If you have good machine work and quality parts then either one should last a good long time.