Wire Alt to batt

70 Duster. Stock wiring in good condition, only add on will be a fuel pump/Holley Sniper. Saw a thread discussing adding a connection from the alternator directly to the batt. I understand this is to reduce the load on the bulkhead connector and under dash wires. Also see the reason to have fuses on the line. What are the cons of adding this connection? What does the ampmeter read, would it indicate a low/overvoltage condition or is it now just a decoration? 3 wire alternator, connection would come off the black wire?