you only need repotting if you start getting feedback noise
I tend to remove the covers of all my pickups over time and swap covers around and never needed to get them potted properly
if youre' really worried about it, you could sell them and then buy a covered set
double cream used bk pickups are hard to find, so you'll probably sell them quick
I was looking for some creamies myself months ago and ended up with zebra pups (that I'm actually not fond of) and added covers later
if they were double cream, I wouldn't bother putting covers on them