That AAW wiring kit is a good one. Concurrent with that installation on my car I moved my battery to the trunk and upgraded the alternator to a 100A power master. I used a 1/0 cable for both the plus and neg battery runs. I ran the neg cable to the pass side cyl head and ground cables to different places to ensure good grounds. That poor 70A alternator you have is surely too small but having good grounds will help your overall electrical system.