The fact that it still has it's original cord is a huge bonus. I have a 508 with a replacement cord that doesn't have the proper round end fitting. I've been keeping an eye out for the correct one for years, but so far no luck. They're kind of dusty so it's hard to tell, but it looks like you may have the right wheels as well, and the correct gray bumper strip is yet another added bonus. That should make your restoration a bit easier. All told it looks like a very nice find. Be sure to share some photos with us when you've had a chance to spruce it up.

Your Kirby 510 was a great find--congrats!  Being in Rochester, MN it may be that the sweeper belonged to a doctor's household and got excellent care.

I'm in Mankato/North Mankato and just saw a Kirby floor polisher--in the original box--at a thrift store here.  Don't remember the price--although it likely wasn't that much.  Judging by the dial and matching Kirby logo, it's at least from the same era if not the same year.  I'm not an expert, but it seems to be in decent shape.  Let me know soon if you want me to purchase it for you; There may be other collectors around the area as another local thrift store had a Kirby Classic that didn't last long on the floor.  

Paul