You can google my past posts with photos. Parallel-reversed diodes with a forward drop ~0.5 V (at ~100 A). I measured ~0.75 V drop in the ammeter circuit at ~50 A output. The diodes I used are rated ~200 A and need a heat sink (can be the copper wires). Don't try it unless you understand basic electricity and DC power. In my post, one reader who doesn't kept arguing with an engineer (me) about resistance, which he didn't understand. A diode has a curved voltage drop vs current curve, which can't be summarized as a linear resistance value.
The 1965 bulkhead has integral buss-bars for the high currents, instead of spade connectors (google images). I retrofit one from a 1965 Fury (ebay harness) to my 1964 Valiant (cut opening 1/8" taller to fit). 1963 also had buss-bars. Seems after going to connectors in 1964, which suffered melted-plastic issues, they walked-back to buss-bars in 1965. In 1966, they moved the wiper motor to the engine bay, requiring a 3rd row of bulkhead terminals, so dropped the buss-bars (perhaps pencil pushers too), so back to melted-plastic. But as long as it lasted thru warranty they had no incentive since new car buyers then changed cars every 3 years. I've seen later Mopars with bulkhead connectors for ALT and BAT but with much larger terminals for those. Adding solid wire feed-thrus is the "Fleet Bypass" which the factory did in taxis and Police cars. Some here did that by drilling thru those positions (or new holes thru bulkhead).
Seems around 1980's, most cars went to wiring bundles direct thru the bulkhead, at least in GM's I've seen at the junkyard. The bulkhead connectors were likely mostly for quicker assembly than maintenance. My 2002 Chrysler minivan kind of regressed to using many connectors at the bottom of the underhood fuse/relay box (still solid wires thru bulkhead). I am guessing that also was for easier assembly. But, causes corrosion problems from rainwater getting in those connectors (not me in CA, but in eastern U.S.).