100/80 is right. I had an old truck years ago that had corroded it's copper wires INSIDE the insulation - the only fix was new cables. Even for our cars, you can buy replacement cables anywhere.

My Graphite's ground cable (buying a generic 15" one) was $11 at Advance Auto. The other cable will run about $40, again, by buying a generic one with about a 40" heavy and 10" smaller cable. (Again, just get a generic cable of lengths that will reach the junction near the battery (light lead) and starter (heavy lead).

I really think 100/80 is probably right here.