l1= [[a,b,c,x,y,z],[a,b,c,x,y,z],[a,b,c,x,y,z],...]
l2= [z,b,c]

while True:
    if ...
        break

l2 = [1,4,20]

l1= [[1,2,3,4,5,6],[7,8,9,10,11,12],[13,14,15,16,17,18]]
l2= [18,14,15]
res1 = [ x for x in l1 if l2 == x[5:6]+x[1:3] ]
res2 = [ x for x in l1 if l2 == x[5:6]+x[1:2] ]

for item in l1:
    здесь выполняем проверку на совпадение

#!/usr/bin/env python
from collections import namedtuple

Map = namedtuple('Map', 'a,b,c,x,y,z')
l1 = [[a,b,c,x,y,z],[a,b,c,x,y,z],[a,b,c,x,y,z],...]
l2 = [1, 4, 20]

z, b = l2[:2] # reference
found_maps = [m for m in map(Map, l1) if z == m.z and b == m.b]

found = next((m for m in map(Map, l1) if z == m.z and b == m.b), None)

l1 = [[1,4,2,7,3,5],[1,8,9,2,5,3,7],[3,2,1,5]]
res = None
for item in l1:
    if 4 in item and 7 in item:
        res = item

for item in l1:
    if (l2[0] in item) and (l2[1] in item):
        res = item

res = []
for item in l1:
    if (l2[0] in item) and (l2[1] in item):
        res.append(item)