Engine Wiring Harness and Electrical issues

[rebelyell]

I got under the hood of my car this weekend and just got sick looking at all the broken and grease covered wires. I decided that since an engine wiring harness was cheap enough, I may as well buy one. So instead of hopping on year one's website and just buying one, I got overwhelmed with options. Here's my problem..

Originally had a 340; now has a 413. Does have A833, doesn't have AC, but I'm going to add it eventually. I don't have rallye gages yet, but I'm going to add Dakota Digital ones soon. Also doesn't have the ammeter bypass (following this tutorial http://www.madelectrical.com/electricaltech/amp-gauges.shtml), but I'm going to do that probably around the same time I swap the harness, install the gages, and move the battery to the trunk. I also plan on adding relays for the headlights and a good stereo with subs in the future. I also found out that the reason I don't have reverse lights is because that part of the harness decided to get a little friendly with the exhaust and melted (of course it did  .) I also plan on adding at least one of these http://www.madelectrical.com/catalog/cn-1.shtml in the engine bay.

And I believe the only thing stopping my horn from working is the missing relay. I'll have to figure out a way to disable the buzzer without the horn. Is there any way to test the horn wiring without the relay? I don't want to wait for the relay when all along the problem was in the steering wheel.

Sooo after all that, I don't know which harness to buy. I think this one will work...am I right? https://www.yearone.com/Product/challenger-cuda/hu112e I am drowning in trying to understand electrical. Thanks for any help you guys can give. I appreciate it.

EDIT: Also, do you guys typically use the factory fuse panel or do you upgrade to something like what painless offers? I think that may be the better option for what I'm wanting to do for the car.

[dodj]

Well if your engine wiring is really bad, buy the new engine harness and install.  Job 1 (I've never bought one, I made mine so I can't give you any recommendation as to which one is best)
Going with Dakota digital eventually doesn't enter into the purchasing decision, re wiring harnesses. You will have to mod that yourself. And your dash harness may be fine. Job 2
The harness that goes to your NSS switch is a very simple one and you can probably repair that yourself with some butt splices, rtv, and heat shrink. Buy new if you want but the repair would be under your car and not visible. Job 3
Adding headlight relays involves cutting into the forward light harness, not the engine harness so it is a different job. Job 4

So instead of being overwhelmed by the overall amount of electrical work, maybe look at the situation as four smaller doable jobs to complete separately.

[RUNCHARGER]

I agree: Electrical on these old cars is very simple, you just have to look at it as individual systems. I don't know what year your car is but an engine harness for a big block E-body is simple to source.
The best approach is to have a look at the whole system and decide if you have to change every wire in the car or just the ones under the hood. Then if you are making a lot of changes in the car decide on modifying a stock harness or maybe go with a complete aftermarket style harness for the whole car.
I've always been able to repair stock harnesses that were in good condition so I can't comment on aftermarket harness brands either.

[rebelyell]

Well if your engine wiring is really bad, buy the new engine harness and install.  Job 1 (I've never bought one, I made mine so I can't give you any recommendation as to which one is best)
Going with Dakota digital eventually doesn't enter into the purchasing decision, re wiring harnesses. You will have to mod that yourself. And your dash harness may be fine. Job 2
The harness that goes to your NSS switch is a very simple one and you can probably repair that yourself with some butt splices, rtv, and heat shrink. Buy new if you want but the repair would be under your car and not visible. Job 3
Adding headlight relays involves cutting into the forward light harness, not the engine harness so it is a different job. Job 4

So instead of being overwhelmed by the overall amount of electrical work, maybe look at the situation as four smaller doable jobs to complete separately.

Maaan. Thanks for that! This puts it into a pretty easy to understand perspective. Electrical anything is just not understandable for me. I need to get a new engine harness for a 71, and they're not too expensive. I have a mass of wires clumped up next to the brake reservoir and it looks bad. I think the first thing I need to do is get the kit to relocate the battery and when I change that wiring, go ahead and bypass the ammeter. Then buy the new engine harness and replace it. Since the headlight relays and the trans pigtail are separate, I can add those after the new harness is in.

[1 Wild R/T]

Biggest thing I'm gonna add is I have no idea why the Mad Electrical site gets so much love, the guy is a hack... I did cleaner work when I was 18.... I'll admit my stuff can look ugly when I'm still figuring stuff out but when it's done it's built to last....I sure wouldn't have a website showing off the hack work Mad Electrical does....

[rebelyell]

I really have no idea what good electrical looks like, honestly. Ive done reading on crimped and soldered connections.

But what's bad about his site? I'm asking honestly out of ignorance.

[71GranCoupe]

Are you going to keep the big block or go back to a small block. From what I gather from your post, you will be adding AC in the future. Is it going to be stock of aftermarket. If aftermarket AC, then a harness without AC would be the one to get. These questions come to mind for me. Year 1 has harnesses that will fit the bill, you just need to figure out what the finished product will be. 

[rebelyell]

Goal is a Gen3 6.4 Hemi. A/C, power steering, hydraulic clutch, etc. Whole 9 yards. That's not going to be for a while though so I need something that works in the meantime.