Carb question

I have 2 sets of carbs from 2 1981 kz750s which I am forming into one bike. The one set of carbs is on a bike that has 77k mi on it (and the bike runs well) and the other has 8k mi on it (and has not run in about a year).

Which carbs should I use... or does it even matter? Do I or should I buy 4 rebuild kits ($50) and rebuild one of the 2 sets of carbs.

Thanks!!!

i would stick with the set that runs well, dont bring another variable into your project.