I built a strut rack for the panel mounted the panel, ran inch and half conduit to the junction box and ran to 1 inch pipe junction box. I pulled the feeder wires over to the junction box and landed in the panel. I removed the existing panel, pulled wire from the new panel to the junction box and terminated all the wires in the junction boxes and the panel. Also extended and tied in existing ground wire that was there but never tied into old panel.