I am changing the service drop from my house to my garage. I have a 200 amp panel in the garage with new meter and am running a 60 amp breaker to the 60 amp panel in the house. I am running 4 wires to the old breaker box in the house via underground. Currently the old, via 1953 Breaker box, is setup for a 3 wire feed, so neutral and ground are all in one "screw down block". Is there a new "ground" block I could purchase and install in the panel to separate the grounds and use my new 4th wire as the ground?

Thanks, Lucas