Derek, I have a Kirby 1C and I am pretty sure that brushroll will work. It has open ends just like the 505 does. I believe the original brushroll was made of metal, the one in the auction looks like its made out of wood. So if you need a brushroll, that one should work. I am not sure why Kirby always starts the model range at 505 in their parts catalogs when the 505 was not that much different than the C models and lots of their parts will interchange. To look at some parts catalogs for Kirby's you would think the first Kirby was the 505 but we all know it wasn't the first. Congrats on your Kirby, you should be proud that you found such a rare model with the original bag. Good luck on the restoration!
Chad