Suddenly no juice

Here's what you are up against

The original charging wire is only no 10 which in house wiring, is only rated for 30A service. But "in the day" you were likely to encounter a 60A alternator!!!

I don't think anyone ever "knew" what the original fuse links were rated for in amps, they had a mopar part number, but they had to handle the alternator amperage. So if you are going to sub say, a big stereo type fuse in there, you need something that will handle your alternator, so probably at least a 40A fuse, and "guesstimate" derated enough to compensate for engine temperature. Are you starting to fell like there are complications?

NAPA used to, back when they were a "real" parts store, used to sell "universal" fuse link wire. I haven't asked them about this in years.