Are 8 week old kittens to old to try and bond with pet rats?

Hi, I have a couple friendly pet rats and I want to get a couple kittens but I don't want them too old that they will try and attack the rats. I know 2-7 weeks is the "imprint" stage for kittens but it's hard to find any rescues adopting out kittens that young, 8 weeks is the youngest I can get. Is that too old to attempt to bond with my rats? The rats don't run around but they live on a high table that has barriers (hard for a cat to get to) but if one really tried, they could get to it if they really wanted to get to the rats and I'm trying to make sure the cats won't ever want to. I'm just not sure if 8 weeks is too old to try and bond with the rats.