65amp wiring/trouble shooting

Since my amp gauge wires melted a bit I'm thinking about an amp gauge bypass. I still have two wires in good shape from another dash to replace the burnt ones but imo this doesnt solve the problem.
The thing is that I have no idea about electrical stuff at all and I don't wanna burn down my car because of bad wiring and I have not really found out where to start working on the bypass. Can you guys help me? I've also thought about to bring the car to a local classic car mechanic to do the job....
The car has a new Voltage Regulator and new battery btw and if the VIN is correct, there's a 65A Heavy Duty Alternator Option listed if not changed over the years.

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Why are you using old wires from somewhere else, just get new 10 or 8 gauge wire. Keep the amp