I purchased a 15' of 1 gauge battery cable (JEGS Performance Products 10291 - JEGS Remote Battery Cable Kit) and it comes with 3' of 1 gauge negative cable. I ran the cable along the passenger side of the frame and left a few feet at each end to connect to alternator and battery. My battery is located in the trunk on the passenger side. The negative cable is bolted to the frame at the rear of the car using dielectric grease and a star washer. I passed both cables through the rear wall with grommets (purchased from McMaster-Carr). I eventually installed a kill switch which interrupts the positive battery cable between the battery and alternator. The kill switch is behind the passenger seat and I can reach it while seated in the driver's seat.
For the flexible fuel line --I ran that along the other frame rail (driver's side) and have a fuel filter mounted inline. I ran all of these before mounting the body---easier for mounting the cushion clamps.