[LS short box]

I don't know about American but the Painless fuse block would not fit in the stock firewall hole do to the larger number of fused connections. I suspect American would be the same. Both companies include wires and fuses for all basic stuff like lights, turn signals and such. Also both include wires for AC, power windows and radios.
The dash wiring the kits supply are fused wires for the gauges but not the sensors.