250K pots as they are both single coils (though one of the P-bass pickup's split coils is RW/RP to the other one to give it noise-cancelling/humbucking properties).
Here are a set on my rear-strung Peavey Cirrus EXP (which was quoted by them to be 35" scale but measures at 34").
You should be able to see where the string thins out. If not, I've marked the end of the thick section on this version. The G string stays the same diameter throughout.
I haven't tried a huge number of bass string types, but they feel reasonable to me.