What size breaker are you feeding the panel with? In your first post you said #6's that would work out to a 60 amp breaker, 3 #6 & 1 #10 ground will go in a 3/4" 60 is usually plenty for a basement. If you want to do 4's that works out to a 80 amp breaker, 3 #4's & #8 ground will go in a 1" not sure about the availability of the 80 amp breaker. Remember to float the neutral and use bushings, bonding on at least one end