……..with the fuse blowing like that, you have a definite , solid short to ground. Use an ohm meter with neg lead connected to frame ground and just start following the wiring from the generator. At the regulator, you'll see some resistance to ground....about 40 ohms...thru' various coils and that's normal. You should never see 0 ohms to ground. 0 ohms = dead short. If you see 0 ohms, start removing wires until the short disappears. With a new wiring harness, chances are it's a wiring error rather than a frayed wire touching the frame.
