Oyster, you are using the alternator charge wire through your firewall to the ammeter as a fusible link. Happy that your lights are brighter, but as RTA notes, its not if, its when..
Mopar dash fires used to be well known to insurance adjusters when there were thousands of these cars on the roads. Before there were big audio amps and hydraulic or air compressor systems to stress a modern electrical system, in the day it was aftermarket air conditioners and motorola radios (think of a whole trunk full of electronics in the day.) I maintained fleet vehicles that had poor installations of these additional loads and cooked the wiring harness. Saw burned jute carpet pad, dash foam, and a lot of wiring insulation. Toxic smoke btw.
The police and special purpose vehicles with the big alternator of the day (about half the output of your Powermaster) used 10 ga charge wiring and a dedicated firewall grommet passthrough to the ammeter and for the battery feed to the fuse block.
