Radio, fuel gauge, ect.. then later, engine, cranking.. died..

[FSHTAIL]

1973 Cuda 340...

Lots of previous owner wiring debauchery.   
Every once and a while the radio and fuel gauge would randomly stop working..   

I tracked it down to a previous owner crimp job.     
I was going to pull the drivers seat to be able to get in there with my soldering gun, but it went in for body and paint in December before I did it and I just got it back 2 weeks ago.

I forgot all about it..   Went to a Cars N Coffee show     So it did it's thing on the way back and I just said "oh yeah, need to do that"

Got back into town, then all of the sudden the engine dies, lost all power, wouldn't even crank over..     nadda...   

I was on an incline at a stop light..        Waved people around, waiting till it was clear and coasted backwards into the driveway of a business.   

The previous owner has an aftermarket fuse block near the battery and I saw that a 30amp blade fuse popped.     
They had a ridiculous size box of fuses in the glove compartment.    guessing this was a thing..           

I checked over wiring and nothing jumped out at me.   

A weekend prior I had to replace both front hard lines going to the soft lines because the fittings were seized to the line.   
There were some wires zip tied to the drivers brake line under the brake booster, I'll start there, but its hard to get to.

Lots of non-factory wiring on the car..       MSD ignition, MSD Pro billet dist, ect.     

My stock 40amp alt kicked the bucket,
so I updated to a Nippondenso 120amp alt and bypassed the AMP gauge to eliminate those issues,
wired up a headlight relay harness to reduce load on the switch..   

This car has been a wiring nightmare from the previous owners..     

Wiring is not my thing..          

factory style starter relay was just replaced last year..   

Any advice? 

[Cuda Cody]

Wish I could help but I've also kept mine stock and they always (knock on wood) seem to work fine.

[73440]

 Did replacing the fuse get you back home ?
Check tightness of your battery cables if you have no power anywhere .
Mine has what looks like almost multiple unused connectors like it's from two to harnesses I thought about drawing an as built wiring diagram out to be able to review it and compare to factory . I had to do crazy jumper wires at the ballast resistor to even get it to run which I know should not be the case to have to do so .

[B5fourspeed]

I would buy a new dash harness and start new with all the wiring.I would remove the entire  dash and check everything.

[dodj]

With non-stock, previous owner modified wiring, there is no way to tell what the issue may be.
Ya kinda have to go wire by wire to figure out what previous owners did. Once you understand the mods, you can troubleshoot the issues.
Personally I would start with the 30amp fuse. Follow the wire it supplies and see what it feeds.