Getting a list of random 64 - bits with fixed XOR value

I need to get a list of random 64 -bits with a fixed XOR value.

I tried :

import random
for i in range(0, 8):
random.getrandbits(64)

This gives me a list of 8 64-bits but it can contain strings of (length < 64) but I want every string to be of exact length of 64 not more or less.