While I agree that the change to a 60 amp generator is possible I would add a caution for anyone attempting this change. First, all the wires in the car are designed to work with the lower current flow so in theory all the main branches, wires that distribute current to any of your new electric users, should increase in diameter. This will allow the wire to carry the same current as before you added the new electrical device and the additional current draw of this new device. So depending on where you tap into the old wiring system will determine how much wire is effected.
If you really need 30 amps to power a whole array of new electrical equipment, it might be a better idea to convert the system to 12 volts. Since the power a device consumes is the voltage times the current, doubling the voltage of the system will half the current flow. This will allow you to use the same wires but will require resistors to reduce the voltage at each of the old 6 volt devices.
If you need to go to 12 volts and 60 amps I would consider a newer model car or a new wire harness.
Increasing the current through an old, frayed wire is dangerous and could start a fire. I would fuse any new device and it wouldn't hurt to fuse all the old ones either.
Brian
