Dang good advice littlebill and for a lot of other reasons as well. I've purchased quite a few sets and I try to stay with either 584's or 2FO's as I have a number of donor sets for each and I need them. As a guess, it takes 3 to make 2 good re-worked ones, stripped threads, broken float posts and a lot more make used carb purchases a 'pig in a poke' purchase as often as not. But; then so it is with an XS 650 purchase as well.
Nah...make that Vintage Motorcycles or perhaps Vintage anything. Best, Blue